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The recent change to quota management for the Western Rock Lobster fishery has resulted in significant changes in fishing behaviour which has affected the ability to use the long standing empirical catch rate indices that have been a major component of the assessment of lobster stocks (e.g. catch rates of legal, undersize and breeding lobsters). A recent FRDC funded study (2009/019) examined the possibility of using alternative data sources unbiased by effort to monitor biomass levels and exploitation rates using change-in-ratio techniques. The project concluded that:
1. The current data sources available to the fishery had too many unknowns including size and sex specific timing of growth and movement to enable the assessment of exploitation rates using these techniques.
2. A robust tag-recapture study using multiple release periods across different fishing seasons could generate independent assessments of legal biomass and exploitation rates providing an additional baseline level to improve the interpretation of post quota catch rate indices.
A comprehensive tag-recapture study would also provide increased resolution of the movement dynamics of lobsters, especially the rate of migration between management zones. Such information is considered vital by industry in their discussions of the potential benefits of voluntarily reducing quotas to generate increased localised catch rates.

Objectives

1. Determine spatially specific exploitation rates and legal biomass levels

2. Increase precision of estimates for movement rates between management zones

3. Improve understanding of the variability of growth throughout the range of the fishery

Final report

ISBN: 978-1-921258-76-3 (Print); 978-1-921258-77-0 (Online)

Author: Simon de Lestang

Final Report • 2020-08-01 • 5.40 MB

2014-023-DLD.pdf

Summary

The West Coast Lobster Managed Fishery (WCRLMF) moved from input to output controls in 2010. This change directly affected the relativity of a number of fisherybased data sources, making assessment of the fishery more problematic. A novel examination of the stock dynamics was required to help ensure the stock assessment and associated management outcomes for this valuable resource were maintained. This study derived estimates of current biomass levels and harvest rates throughout the WCRLMF based on the release (over 40,000) of tagged Western Rock Lobsters (Panulirus cygnus) and the recapture of tagged lobsters, using a multi-stage modelling process. Components of this study, such as tag loss and reporting rates, were initially independently examined, before a generalised “Brownie” tag-recapture (BTR) model was implemented that provided an assessment on a fishery-wide basis. Finally a novel purpose-built individual-based model (IBM) was developed that was capable of producing estimates of biomass and harvest rates on finer spatial and temporal scale, as well as providing estimates of migration and growth.

Mitigation measures to reduce entanglements of migrating whales with commercial fishing gear

Project number: 2014-004

Project Status:

Completed

Budget expenditure: $499,999.00

Principal Investigator: Jason How

Organisation: Department of Primary Industries and Regional Development (DPIRD) WA

Project start/end date: 1 May 2014 - 7 Jul 2016

Contact:

FRDC

TAGS

SPECIES

Need

Whale entanglements in the western rock lobster (WRL) fishery have increased dramatically with changes in fishing times from a move to a quota. The recent commonwealth Department for the Environment (DE) assessment removed the fishery from five-year export approval, granting a two-year Wildlife Trade Order (WTO) with conditions on whale entanglements. Subsequent correspondence from the Department of Fisheries (DoF) and DE requested information from industry as to what actions will undertaken for the 2014 and 2013 humpback migrations respectively. DoF correspondence indicated a seasonal closure may be implemented ‘in the absence of specific alternative action(s)’. A closure during the humpback migration (1 May-30 Nov) would concentrate fishing into the remaining 5 months resulting in a reduced beach price. Winter beach prices are ~$70/kg, with a move from this high value period into a condensed season reducing GVP by ~$50 million.
TRF project (2013-037) addresses the immediate aspects of the WTO conditions, required by 31 March 2014. Industry groups, while cognizant of the need to address the issue of whale
entanglements are reluctant to proceed with the introduction of gear modifications without a clear scientific rationale behind their testing.
Project 2013-037 is a preliminary study and with its initiations after the 2013 humpback migration has begun, detailed gear testing and migration information was not possible. However it is planned to identify a number of viable mitigation options that are worthy of detailed evaluation in 2014. This project extends on Project 2013-037 addresses the longer term (2014-2015) DE conditions, which would enable year-round market access.

Objectives

1. Determine and implement appropriate gear modifications and management changes to reduce entanglements with migrating humpback whales

2. Produce fine-spatial and temporal information on whale migrations along the west coast of Western Australia necessary for a tailored spatio-temporal closures and/or areas for gear modifications.

3. Provide clear scientific methods behind the testing of selected gear modifications to reduce whale entanglements

4. Incorporate any new practices that may reduce entanglements with migrating whales in the CoP for the fishery and ensure its extension and adoption

Final report

ISBN: 978-1-921258-43-5

Authors: J How D Coughran M Double K Rushworth B Hebiton J Smith J Harrison M. Taylor D Paton G McPherson C McPherson A Recalde Salas C Salgado-Kent and S de Lestang

Final Report • 2020-03-01 • 5.85 MB

2014-004-DLD.pdf

Summary

This project provided a robust assessment that gear modifications introduced into the WCRLMF and octopus fisheries have reduced the number of reported entanglements. The management arrangements around the implementation of these modifications are appropriate in light on the new spatial and temporal information on the migratory behaviours of humpback whales off the west Australian coast. Therefore, it is recommended that the current management arrangements that are in place to reduce whale entanglements remain. It should be noted however, that while gear modifications have been effective, the whale population off the west Australian coast is predicated to continue to increase. As a result, entanglements may increase in the future as a result of this population increase, and additional research may be required to assess possible additional gear modifications or management arrangements.

PROJECT NUMBER • 2009-714.10

PROJECT STATUS:

COMPLETED

Seafood CRC: decision-support tools for economic optimisation of western rocklobster

The Western Rocklobster fishery was one of the first to be made limited entry with the number of licences restricted since 1963. Historically, the main focus of the assessment and management of the fishery has been on the status of the breeding stock to ensure biological sustainability. In the...

ORGANISATION:

Department of Primary Industries and Regional Development (DPIRD) WA

TAGS

SPECIES

PROJECT NUMBER • 2016-124

PROJECT STATUS: