27 results
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Environment
People
Industry
Environment
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PROJECT NUMBER • 2022-075
PROJECT STATUS:
COMPLETED

National Workshop to develop a regional collaborative plan to control the invasive Longspined Sea Urchin (Centrostephanus rodgersii)

The 2023 National Centrostephanus Workshop was convened by the Department of Natural Resources and Environment Tasmania. The workshop brought together 130 representatives from industry, government, research, Aboriginal communities, recreational fishing groups, and the community to: • Identify...
ORGANISATION:
Department of Natural Resources and Environment Tasmania (NRE TAS)
TAGS
Rac Vic
Rac Tas
Rac Nsw
Invasive Species
Climate Change
SPECIES
Sea Urchins
Environment
Industry
Industry
Industry
Blank
PROJECT NUMBER • 2018-016
PROJECT STATUS:
COMPLETED

Improving data on Aboriginal and Torres Strait Islander marine resource use to inform decision-making

Through two national workshops, Indigenous community and agency representatives and researchers discussed issues around collecting, sharing and ownership of Indigenous fishing data. Challenges and opportunities were shared from all perspectives and expertise, knowledge and information came together...
ORGANISATION:
Department of Primary Industries and Regions South Australia (PIRSA)
TAGS
Wild Catch
Survey
Recreational Fishing
Rac Cmwth
Marine Park
SPECIES
Mulloway
Black Bream
Snapper
Australian Herring
Sand Whiting
Industry
Adoption
PROJECT NUMBER • 2017-049
PROJECT STATUS:
COMPLETED

Monitoring abalone juvenile abundance following removal of Centrostephanus and translocation

A new system of Abalone recruitment modules (ARMs) have proven to be successful in collecting juvenile abalone in Tasmanian waters. This design was subsequently transferred to the Eastern Zone, Victoria, where IMAS staff and Eastern Zone Abalone Industry Association (EZIZA) members installed ARMs at...
ORGANISATION:
University of Tasmania (UTAS)
TAGS
Reproduction
Rac Vic
Fisheries Management
Depredation
SPECIES
Blacklip Abalone
Sea Urchins
Industry
Industry
PROJECT NUMBER • 2016-208
PROJECT STATUS:
COMPLETED

Waste to profit in urchin fisheries: developing business opportunities to ensure fishery sustainability and safeguard reef dependent fisheries from destructive urchin grazing

This report examines two potential applications of Longspined Sea Urchin (Centrostephanus rodgersii) via pitot scale trials; processing waste as an agricultural fertiliser and use as Southern Rock Lobster bait. The biochemical composition of Longspined Sea Urchin waste products was analysed, and the...
ORGANISATION:
University of Tasmania (UTAS)
TAGS
Rac Vic
Rac Tas
SPECIES
Sea Urchins

Rebuilding abalone populations to limit impacts of the spread of urchins, abalone viral ganglioneuritis and other external impacts

Project number: 2014-224
Project Status:
Current
Budget expenditure: $340,000.00
Principal Investigator: Harry F. Peeters
Organisation: Western Abalone Divers Association (WADA)
Project start/end date: 7 Aug 2014 - 29 Jun 2017
Contact:
FRDC
TAGS
Resource Rehabilitation
Rac Vic
Invasive Species
Habitat
Ecosystem
SPECIES
Blacklip Abalone
Sea Urchins

Need

Local abalone populations can be severely depleted by a range of impacts, including loss of habitat from the spread of sea urchins, diseases such as AVG and Perkinsus, environmental change and theft. Many of these impacts have been increasing for over a decade, although impacts of sea urchins on abalone and reef habitats in the last 5 years have been spreading in eastern Victoria, and appear related to climate change. Similarly, impacts remain from the spread of AVG through western Victoria.

There is evidence that production from commercial abalone fisheries continues to be reduced by the ongoing increase in external impacts to local abalone populations. While tools have been developed at a small-scale to help recover abalone populations, there is a strong need to investigate, implement and assess these at a larger scale to be able to minimise further impacts and recover productivity of abalone populations.

VicFRAB this year rated its highest priority to facilitate the investigation of translocating abalone to address declines caused by urchins and disease. Similarly, the NSW DPI strategic research plan identifies a priority to "determine methods to restore depleted reefs of abalone through techniques such as transplants, habitat rehabilitation and reseeding". The ACA Strategic Plan also details actions to plan and support remedial action to reduce the impact of pests, disease and theft on abalone.

The ongoing spread of impacts to local abalone populations is having a broad impact on shallow reef habitats. Small-scale research has demonstrated the potential of recovery techniques, but have not been implemented at a broad scale to actually attempt to recover lost productivity. This project will address the need to investigate the scaling up of recovery techniques, and their costs and long-term benefits, in an attempt to recovery lost productivity from abalone populations in south east Australia.

Objectives

1. Identify and prioritise sites and strategies for assessment to recover shallow reef habitat and productive abalone populations
2. Assess strategies for recovery of shallow reef habitats and productive abalone populations.
3. Develop a business plan to guide ongoing future actions and strategies to extend the project outputs and rebuild abalone populations.

Can commercial harvest of long-spined sea urchins reduce the impact of urchin grazing on abalone and lobster fisheries?

Project number: 2013-026
Project Status:
Completed
Budget expenditure: $297,908.54
Principal Investigator: Craig Mundy
Organisation: University of Tasmania (UTAS)
Project start/end date: 31 Aug 2013 - 16 Oct 2016
Contact:
FRDC
TAGS
Rac Tas
Harvest Strategy
Fishing Effort
SPECIES
Blacklip Abalone
Sea Urchins

Need

The long-spined sea urchin Centrostrephanus rodgersii has gradually increased in extent and biomass on the East coast of Tasmania over the past three decades. Options for direct and indirect intervention are being considered to limit numbers of this urchin to that required to minimise the destruction of the kelp and understory habitat essential for other benthic species such as abalone and rock lobster. Over the past two years a fledgling urchin harvest industry has developed in Tasmania, with the potential for market demands to create a significant fishery in terms of harvest biomass. Whether harvesting of urchins is beneficial (synergistic) to existing fisheries needs to be determined to inform development of a Harvest Strategy of all species reliant on healthy shallow (20m) sub-tidal ecosystems. The efficacy of commercial urchin harvesting as a ‘control tool’ is dependent on the degree of spatial overlap with other fisheries (co-dependent on habitat), the capacity of urchin harvesting to minimise localised destructive grazing, and, whether the urchin harvest is economically sustainable given the practical limitations of harvesting at depth.

Objectives

1. Determine spatial location and extent of overlap between Centrostephanus and existing fisheries
2. Application of coastal exposure indices for identifying potential urchin harvest locations
3. Determine dive profile strategies to enable safe harvest of urchins at depths greater than 15m

Final report

Authors: Keane J.P. Mundy C. Porteus M. Johnson O.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.
Final Report • 2019-03-01 • 1.88 MB
2013-026-DLD.pdf

Summary

At low-levels of exploitation, commercial harvesting of long-spined sea urchins was found to prevent increase in urchin density. Adjacent unfished locations experienced an increase in both urchin density and grazed area over the 2014 – 2016 study period. Research sampling of populations remaining on reefs after fishing also found that mean urchin Test diameter and urchin age was smaller and younger respectively than on nearby unfished reefs, further supporting there is a measurable effect of urchin fishing on urchin populations even at low exploitation rates. These results demonstrate a clear potential for urchin fishing to reduce destructive grazing by urchins, or at least prevent further expansion of existing grazed areas even under a regime of low
fishing pressure.
 
The Tasmanian commercial fishery of long-spined urchin either directly overlaps or is immediately adjacent to commercially fished abalone reefs. As the presence of barrens has a clear negative association with abalone abundance, the potential for urchin fishing to lower urchin densities in key reef habitats highlights the importance of an ongoing long-spined urchin fishery for protecting key abalone fishing grounds (recreational and commercial). The ability to capture fine-scale spatial data on both urchin and abalone fisheries was critical to evaluating the potential for urchin fishing to benefit the abalone fishery. A long-term strategy for fine-scale data collection using passive GPS and Depth data loggers will be fundamental to ongoing assessment of the benefits of urchin fishing to the abalone fishery, but also to the broader users of shallow coastal reef systems in Eastern Australia.There is also the potential for positive-feedback loops from urchin fishing, with reduction in densities increasing roe production and output, and therefore ensure that the industry can remain economically sustainable.
 
Cartographic Exposure Index software developed during this project showed some capacity to identify coastlines at risk to destructive grazing, but further data collection to underpin the predictive model is required. Production of a high-resolution bathymetric map of key coastal reefs is considered to be a high priority for ongoing spatial mapping and analysis of the expansion of the urchin fishery and its consequent effects on urchin density.
 
There is a clear benefit to the urchin fishers if they switch from compressed air to using Nitrox gas for diving safety and access to greater reef area. Current beach price and likely decline in catch rates as the fishery expands however, will mean that investment in Nitrox based breathing systems may be economically marginal. From a health perspective, a switch to Nitrox while retaining the current bottom time would have clear safety benefits.
 
This study demonstrated positive benefits for abalone habitat at very-low urchin exploitation levels, with the extent and spatial magnitude of benefits expected to rapidly increase with increasing urchin exploitation. It is unlikely that commercial harvesting will lead to eradication of the long-spined sea urchin, but there is clear potential for commercial fishing to be a primary contributor to mitigating the destructive grazing of this species.

Tactical Research Fund: Limiting impacts of the spread of urchins by rebuilding abalone populations

Project number: 2012-058
Project Status:
Completed
Budget expenditure: $42,000.00
Principal Investigator: Geoff Ellis
Organisation: Eastern Zone Abalone Industry Association (EZAIA)
Project start/end date: 31 Jul 2013 - 22 Aug 2014
Contact:
FRDC
TAGS
Stock Assessment
Reproduction
SPECIES
Sea Urchins

Need

The impact of urchins (i.e. Centrostephanus) on reef habitats in south-east Australia has been increasing for over a decade, and may be related to climate change (FRDC 2009/070). Urchins can clear and maintain areas of reef free from macro-algae, and reduce the productivity of abalone populations and other reef species. Extensive research projects to monitor urchin populations and reduce their impacts have been completed or are under-way in NSW, Victoria and Tasmania. There is an urgent need to consolidate the findings of these research projects, and to quickly plan and coordinate the on-going development of responses to the spread of urchins.

There is evidence that production from commercial fisheries in NSW, Vic and Tas has been reduced by the spread of urchins. Small-scale clearance of urchins, and the translocation of abalone, has demonstrated the ability to recover abalone populations impacted by urchins, but consequent return of production has not yet been demonstrated in any fishery. In eastern Victoria, a joint project between Industry and Government has recently seen commercial-scale removal of urchins from previously-productive abalone reef, and the consequent recovery of appropriate habitat for abalone over a large-scale. There is now a tactical opportunity and strong need to take advantage of these removals before urchins re-invade, to demonstrate that past research can be scaled up to larger areas of reef and recovery of larger abalone populations, with the intent to maintain them over long-periods to demonstrate outcomes of sustained productivity.

Recent observations indicate urchins have also spread to western Victoria, where abalone are still recovering from Abalone Viral Ganglioneuritis. There is also an urgent need to both develop a survey to estimate the extent of Centrostephanus in western Victoria, and to investigate the potential of translocating abalone at a large-scale to re-establish populations in depleted areas, before urchins spread further.

Objectives

1. Facilitate a workshop to coordinate existing research findings among jurisdictions, and plan further development and extension.
2. Implement the short-term outcomes of the workshop, particularly related to development of a survey to monitor spread of Centrostephanus.

Tactical Research Fund: trial of an industry implemented, spatially discrete eradication/control program for Centrostephanus rodgersii in Tasmania

Project number: 2011-087
Project Status:
Completed
Budget expenditure: $133,200.78
Principal Investigator: Sean Tracey
Organisation: University of Tasmania (UTAS)
Project start/end date: 30 Jun 2012 - 29 Jan 2014
Contact:
FRDC
TAGS
Sustainability
Rac Tas
Modelling
Invasive Species
Food Safety
SPECIES
Blacklip Abalone
Sea Urchins

Need

Over the last three decades the distribution of long-spined sea urchin has extended from its native range in NSW down the east coast of Tasmania and west through Victoria. The impact of this range expansion is expected to intensify. This large sea urchin overgrazes seaweeds and invertebrates on rocky reefs, causing catastrophic regime shifts in the coastal ecosystems. The 'barren' habitats that are left after the establishment of an urchin population are unable to support commercial or recreational fisheries for abalone or rock lobster among other species. Therefore the incursion of this species into non-endemic regions pose a significant threat to the integrity of shallow reef ecosystems and the associated biodiversity and fisheries these regions support.

Objectives

1. Determine the effectiveness of divers physically destroying urchins in situ to either eradicate or control spatially discrete aggregations to allow the re-establishment of native flora and fauna
2. Determine the cost effectiveness of objective 1 in regard to lost production for commercial, recreational and customary harvests.

Final report

ISBN: 978-1-86295-949-1
Authors: Sean Tracey Craig Mundy Travis Baulch Martin Marzloff Klaas Hartmann Scott Ling John Tisdell
Final Report • 2015-05-05 • 27.38 MB
2011-087-DLD.pdf

Summary

The long-spined sea urchin, Centrostephanus rodgersii has expanded its distribution southwards from southern New South Wales, through Eastern Victoria, the Bass Strait Islands and down the east coast of Tasmania. In some areas of Tasmania abundance of C. rodgersii has increased substantially, even to sufficient densities to form destructive grazing aggregations, removing the overstory macroalgae that are essential component of a healthy reef ecosystem. The degradation of these coastal reef systems has serious implication not only to biodiversity conservation and ecosystem value, but also to high value fisheries, with the potential to significantly compromise sustainable fisheries management practices.
This project aims to test the effectiveness of systematic culling in discrete areas as a strategy to reduce the density of C. rodgersii to minimise the potential for destructive over grazing, and secondly provide an estimate of the cost of culling areas of reef on the east coast of Tasmania.
Methodology: To test the effectiveness of culling in discrete area the project applied an experimental design utilising multiple treatment (n = 8) and control plots (n = 4), each 1,500 m2. These plots were assessed using a combination of randomised belt transects and census counts. Approximately two weeks post-culling the density of C. rodgersii within the eight treatment and four control plots was assessed using randomised belt transects, followed immediately by a second systematic cull within four of the treatment plots. Approximately 12 months after the initial culling exercise the density of C. rodgersii in all 12 plots was re-assessed using randomised belt transects, and the eight treatment plots further assessed by a systematic census count.
 
Two bio-economic models were developed to determine the cost of culling areas across the east coast of Tasmania, as well as sub‐areas (case study areas). The models were developed based on information on the cost of employing commercial divers to cull areas of reef down to 20 m, beyond which dive times were considered a limitation to implement a cost-effective culling program.
 
Results: Systematic culling of Centrostephanus rodgersii in spatially discrete plots in Wineglass Bay on the east coast of Tasmania was highly successful with average urchin density reduced from 1.51 to 0.13 urchin.m-2 within treatment plots when assessed approximately one year post‐culling.
Systematic culling was also effective at significantly reducing the patchiness of urchin distribution, where high abundance patches are, in theory, more likely to destructively over graze a reef area.
 
Four treatment plots were culled twice and the reduction in urchin abundance compared with the other four plots that were only culled once. The result was that there was no significant difference in the reduction of C. rodgersii between the single and multiple cull treatments.

 

The cost of manually controlling an invasive species in the marine environment is inherently expensive due to the costs associated with mobilising logistics to a target area, and secondly the limitations of diver time in the water. In this report we present models that can be used to generate cost estimates to cull a given area based on urchin density and dive depth, with the maximum depth chosen having a great effect on the overall cost. A local scale model estimates the maximum cost to cull Wineglass Bay to a depth of 20 m at $1,617,802, based on a constant density estimate of 1.5 urchins.m‐2. The cost to cull reef areas within Fortescue Bay to a maximum of 20 m using the same model at $877,019 based on a constant density of 0.29 urchins.m-2.

 

This report shows that systematic culling can significantly reduce the density of C. rodgersii in discrete areas. The implications of these findings are that culling can be considered a viable method in the management strategy evaluation of controlling the deleterious effects of C. rodgersii. The costing models provide tools to estimate the direct cost of implementing a culling strategy at a range of spatial scales across the east coast and can be manipulated to provide a bio-geographically accurate estimate of cost depending on the area (and size of area) selected.

FRDC-DCCEE: preadapting a Tasmanian coastal ecosystem to ongoing climate change through reintroduction of a locally extinct species

Project number: 2010-564
Project Status:
Completed
Budget expenditure: $180,000.00
Principal Investigator: Nicholas Bax
Organisation: University of Tasmania (UTAS)
Project start/end date: 23 Dec 2010 - 29 Dec 2012
Contact:
FRDC
TAGS
Threatened Endangered Protected Species
Resource Access And Allocation
Oceanography
Fisheries Management
Climate Change
SPECIES
Wrasses
Sea Urchins

Need

Changing marine climate is driving species south, impacting recreational and commercial fishers and biodiversity and conservation values. At the same time, the local environment is changing the capacity of ecosystems to respond to an increasing array of environmental pressures. Is adapting our social and economic systems the only option for conservation managers and planners, or can we increase the resilience of the local environment to the increasing pressures? Can we gain time, or could we even influence the trajectory of change?

Assisted translocation (within the historic range) may preserve isolated populations of terrestrial animals. Is this appropriate in marine environments? Translocation typically emphasizes individual species. Would a more influential approach be to translocate species that would benefit the receiving ecosystem? We propose to develop the protocols and safeguards to reintroduce a key temperate reef predator – the blue groper – that became locally extinct in Tasmania over a century ago. The blue groper is a temperate wrasse that grows to over 50kg. It is a charismatic component of the NSW fish fauna interacting with snorkelers, divers and recreational fishers. Its diet includes the long-spined sea urchin currently establishing in Tasmania. Rearing and transporting similar species is well understood and the sequential hermaphroditism potentially provides the opportunity to introduce only larger male fish.

This will be a test case to determine whether translocating marine species is a viable option to improve resilience to climate change and what processes, knowledge and changes in policy are required before attempting this. Our application is regional but the implications are national (and global). While we are using the blue groper as the focus for our work, we will be exploring more generally the opportunities for assisted translocation, local enhancement to increase the resilience of temperate reefs, and the protocols and safeguards that would be required.

Objectives

1. Develop and promote a national framework to evaluate potential translocations of native marine species.
2. Determine the feasibility of reintroducing blue groper as a test case.
3. Design a monitoring and evaluation program to determine the effects of a trial re-introduction
4. Reach the critical decision point on whether to re-establish blue groper in Tasmania, or to take an alternative approach indicated by the research. Develop a proposal to support this outome.

Final report

ISBN: 978-1-922173-56-0
Author: Nic Bax
Final Report • 2013-02-20 • 7.36 MB
2010-564-DLD.pdf

FRDC-DCCEE: adaptive management of temperate reefs to minimise effects of climate change: developing new effective approaches for ecological monitoring and predictive modelling

Project number: 2010-506
Project Status:
Completed
Budget expenditure: $330,000.00
Principal Investigator: Neville Barrett
Organisation: University of Tasmania (UTAS)
Project start/end date: 31 Dec 2010 - 30 Dec 2013
Contact:
FRDC
TAGS
Survey
Population Dynamics
Oceanography
Modelling
Marine Park
SPECIES
Sea Urchins

Need

Waters along Australia’s most densely populated east coast are warming at 3.8 times the global average rate, which is the most rapid change in the Southern Hemisphere. Ecosystems in this region are likely to be severely impacted by climate change and significant biodiversity change is expected. The rapid nature of these ecosystem changes will require science-based decisions about where, how and when to apply adaptive management interventions. Predictive models have high uncertainty when extrapolated into new conditions, as do CC scenario models. Unless protocols for tracking and predicting ecological changes are well informed, the remote nature of marine habitats, with associated difficulties and expense when mapping biodiversity assets, will inevitably translate to sub-optimal management interventions. Potential management interventions could include targeted spatial closures to protect vulnerable habitats, targeted translocation of key predators, direct manipulation of abundances of threatening and or threatened species.Our project will address these challenges using Australia’s east coast as it is the region of greatest change and hence under the most imminent threat. Using the longest available worldwide (18-yr) ecological reef data record of fishes, invertebrates and macro-algae in marine reserves, we will identify thresholds in ecological responses such as significant assemblage shifts, kelp decline and predator-prey relationships. These outputs combined with future climate scenarios will empower, state management and NRM agencies with mproved capacity to build ecosystem resilience through spatial management actions. The project addresses three NCCARP priority questions by: (3.1) identifying priority ecosystems and species most vulnerable in this globally significant warming hotspot; (2.1) identifying vulnerable inshore reef species of commercial fisheries importance (including southern rock lobster, abalone, and temperate wrasses) and priority locations for adaptive management; and (3.2) clarifying management benefits from one intervention strategy – MPAs – for enhancing resilience of temperate ecosystems.

Objectives

1. To collate and analyse the long-term marine ecological data records for southeast Australian reefs and use these to quantitatively describe relationships between species’ distribution and abundance and changes in ocean temperature, salinity and EAC position as key drivers of climate change
2. To identify optimal locations and species for monitoring programs (including Reef Life Survey – a cost-effective, ecological monitoring program using trained recreational divers – and comparable agency-based programs) to best inform adaptive management via delivery of up-to-date relevant information
3. To assess the costs and benefits of existing temperate Marine Protected Areas for biodiversity-conservation management in response to CC and evaluate the robustness of adaptive management frameworks given uncertainty in predictions
and
4. To develop models that quantify and predict the impacts of climate change on inshore reef communities of fishes, invertebrates and macroalgae across the southeast Australian region so that potential responses to change can be identified, considered and developed appropriately.

Final report

ISBN: 978-1-86295-770-1
Final Report • 2014-09-15 • 13.90 MB
2010-506-DLD.pdf

Project products

Fact Sheet • 2.39 MB
2010-506 - Adaptive Management of Temperate Reefs for Climate Change - New Approaches for Ecological Monitoring and Predictive Modelling.pdf

Sponsorship of 13th International Echinoderm Conference

Project number: 2008-348
Project Status:
Completed
Budget expenditure: $0.00
Principal Investigator: Craig Johnson
Organisation: University of Tasmania (UTAS)
Project start/end date: 9 Sep 2008 - 29 Apr 2009
Contact:
FRDC
TAGS
Oceanography
Habitat
Food Web
Conference
Climate Change
SPECIES
Tropical Abalone
Blacklip Abalone
Roe's Abalone
Greenlip Abalone
Sea Urchins

Need

The conference theme - Echinoderms in a Changing World - focuses on major current issues including climate change and ocean acidification, as well as incorporating echinoderm physiology, biogeography, genetics, genomes and development as major focal points in marine research. Tasmania is a highly appropriate location given international attention to the circumstances of climate change driving range extension of an echinoderm into Tasmanian waters, where it poses a significant threat to biodiversity of shallow rocky reef systems and the sustainability of associated fisheries.

Objectives

1. To provide partner sponsorship to ensure a successful conference

Rebuilding Ecosystem Resilience: assessment of management options to minimise formation of ‘barrens’ habitat by the long-spined sea urchin (Centrostephanus rodgersii) in Tasmania

Project number: 2007-045
Project Status:
Completed
Budget expenditure: $828,551.00
Principal Investigator: Craig Johnson
Organisation: University of Tasmania (UTAS)
Project start/end date: 19 Apr 2008 - 30 Jun 2011
Contact:
FRDC
TAGS
Invasive Species
Habitat
SPECIES
Southern Rock Lobster
Blacklip Abalone
Sea Urchins

Need

There is clearly potential for C. rodgersii barrens to cover ~50% of nearshore reefs on the east coast of Tasmania, as is already the case in NSW and the Kent Group in Bass Strait. This would reduce both the Tasmanian abalone and rock lobster fisheries by ~15%, with a loss of value totalling ~$25M (before processing). The need for a management response is self evident.

Large rock lobsters (=135 mm CL) are the key predators of C. rodgersii in Tasmania, and experiments have shown clearly they can prevent sea urchin populations from building to the point where overgrazing occurs. There is urgent need to assess the viability of controlling C. rodgersii populations through changing current management of the rock lobster fishery, and through targeted removal by divers as a tactical response on small scales.

However, before management instruments are invoked in an attempt to minimise the risk of further development of barrens habitat or rehabilitate existing barrens, it is imperative to carefully evaluate the effectiveness of potential management strategies. The proposed research will provide the necessary information and knowledge base to enable robust management decisions.

The proposed work has strong support from managers and the fishing industry in Tasmania, is acknowledged as a high priority by the relevant RAGs, and addresses several high priorities on both the State and TAFI strategic research plans.

Objectives

1. To assess the effectiveness of translocating large rock lobsters (=135 mm CL) en masse as means of preventing formation of incipient barrens and rehabilitating incipient and extensive barrens.
2. To assess the effectiveness of a range of management options (e.g. imposing upper size limits and spatial management) in building the biomass of large (=135 mm CL) rock lobsters to levels sufficient to limit C. rodgersii populations.
3. To assess the effectiveness of killing or removing sea urchins by abalone divers during the conduct of their fishing activity, as a means of preventing formation of incipient barrens and rehabilitating incipient and extensive barrens.

Final report

ISBN: 978‐1‐86295‐712‐1
Final Report • 2015-01-21 • 8.97 MB
2007-045-DLD.pdf

Summary

By overgrazing seaweeds and sessile invertebrates, essentially back to bare rock, the advent of the long‐spined sea urchin Centrostephanus rodgersii in eastern Tasmanian waters poses a significant threat to the integrity, productivity and biodiversity of shallow (<40 m) rocky reef systems and the valuable fisheries (principally abalone and rock lobster) that they support. The present research examined means of managing this threat at small, medium and large spatial scales.

Divers have the opportunity to limit C. rodgersii densities at local scales by culling or harvesting to prevent formation or expansion of urchins ‘barrens’ habitat at incipient stages when barrens occur as small patches in seaweed beds. To ensure sufficient time for seaweed recovery in cleared patches, local control in this way requires that sea urchins show a high fidelity to their particular incipient barrens patch so that once a patch is cleared of sea urchins there is little likelihood of it being quickly recolonised by other individuals from nearby patches. We found that on all types of barrens habitat C. rodgersii is highly nocturnal in behaviour, and has a strong tendency to return to its home crevice at the end of each night. Individuals in incipient barrens patches show strong fidelity to their patch over periods of several months, with little tendency to cross the boundary between barrens and seaweed cover, such that mean net movement in small patches is less than 1 m in 3 months. Accordingly, there is little tendency to migrate among patches, which is explained in part by laboratory experiments indicating that C. rodgersii lacks a directional chemosensory response to either macroalgae or conspecifics. Thus, urchin behaviour suggests that localised culling is likely to be effective in rehabilitating existing incipient barrens patches and reducing risk of further patches forming.

However, this outcome is unlikely to be achieved by the activity of professional divers culling urchins while fishing for abalone. Our trials indicate that abalone divers are motivated primarily by catching abalone. Thus, while they can be effective at culling urchins from the individual incipient barrens patches they encounter so that seaweeds recover in these particular patches, the number of patches they are able to visit while fishing through an area is small so that the overall effect of their culling activity within the area that they fish is not detectable except at the scale of individual patches visited. Given typical revisitation times to fish in a given area, divers culling urchins while fishing abalone are unlikely to provide meaningful local control of urchin populations. In this context, systematic and targeted harvesting of urchins as an independent industry, or killing urchins with quicklime or by deploying divers whose sole task is to cull urchins, is likely to be much more effective (but at added cost).

Abalone divers culling C. rodgersii while fishing can be successful in helping to regenerate seaweed cover on particular targeted barrens patches, but this is unlikely to have any significant effect in controlling urchins at the level of dive sites or reefs. Abalone divers should be encouraged to cull C. rodgersii while fishing.

Keywords: Sea urchin, Centrostephanus rodgersii, rock lobster, Jasus edwardsii, abalone, Haliotis rubra, sea urchin barrens habitat, ecosystem based management, modelling, stock rebuilding, maximum economic yield.

Environment

Aquaculture nutrition subprogram: post harvest enhancement of sea urchin roe for the Japanese market

Project number: 1999-319
Project Status:
Completed
Budget expenditure: $138,238.00
Principal Investigator: Richard Musgrove
Organisation: SARDI Food Safety and Innovation
Project start/end date: 28 Jun 2000 - 27 May 2005
Contact:
FRDC
TAGS
Stock Assessment
Reproduction
Post Harvest
Physiology
Nutrition
SPECIES
Sea Urchins

Need

Development of urchin fisheries in Australia is currently limited by economic viability due to low recovery rates. This fishery has a large opportunity to expand given:
1. There is a large sea urchin resource
2. The high price urchin roe fetches
3. Low cost of fishing (relatively shallow water).

The opportunity to develop this fishery into a highly profitable one is dependent on the development of innovative solutions. This proposal examines the potential for enhancing recovery rates using supplementary feeding for short periods. If this can be done cost effectively it opens the opportunity to dramatically increase the profitability and size of this fishery. Without this technology the urchin fishery will not fully develop. With this technology the fishery has the potential to be worth tens of millions. This project has been initiated by support through both existing permit holders and Aquaculturists.

Objectives

1. Determining the feasibility of postharvest enhancement of sea urchin, Heliocidaris erythrogramma, roe through the use of commercially available feeds.
2. Determine the environmental conditions (time and temperature) under which roe enhancement can be optimised.
3. Evaluate photoperiod manipulation of the gametogenic cycle as a method of increasing the availability of the highest quality roe.
4. Evaluate the best commercial growout options by assessing the technical and relative economic feasibility of both land based (eg. abalone) and in-water sub-tidal cage (eg. polyculture with Pacific Oysters).
5. Evaluate existing commercially available sea urchin diets (USA) and Australian abalone diets for their suitability and applicability to Heliocidaris erythrogramma and recommend directions for the refinement of diets specifically suited to sea urchins in Australia.
6. Determine future research needs for the industry.

Final report

ISBN: 073085311X
Author: Richard Musgrove
Final Report • 2005-02-25 • 9.66 MB
1999-319-DLD.pdf
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