Understanding the factors contributing to decreased school prawn productivity in Camden Haven Estuary and associated lakes, to target ameliorative actions

Project number: 2015-011
Project Status:
Completed
Budget expenditure: $107,078.00
Principal Investigator: Matt D. Taylor
Organisation: Department of Primary Industries and Regional Development (NSW)
Project start/end date: 14 Jul 2015 - 14 Mar 2018
Contact:
FRDC

Need

This project directly addresses Priority 20 in Program 1 (Environment), which was identified as a research priority by the NSW Fisheries Research Advisory Board for 2015. This priority arose through ongoing concerns about declines in School prawn productivity that fishers have conveyed to NSW commercial fisheries managers and peak industry bodies, particularly fishers in the north coast region of NSW. This issue is not confined to one estuary, and declining productivity of School prawns in some areas is an issue which percolates through all stakeholders in the NSW fishing industry, including individual fishing businesses and fishing cooperatives at the local scale, as well as the Professional Fishermens Association and other peak bodies, and recreational fishers whose primary bait supply is underpinned by School prawn harvest.

Consequently, this project has been designed to address two key needs identified by industry: 1) An improved understanding of the specific issues within Camden Haven estuary, to allow management to strategically target ameliorative actions within the catchment and estuary itself; and 2) A broader understanding of how catchment-based activities could be affecting School (and other) prawn stocks along the New South Wales coast, through adverse effects on water quality. Restoration of the School prawn fishery in Camden Haven and other estuaries is essential to the continued livelihoods of estuary fishers, and provision of quality seafood product for both consumption and bait markets. However, the factors which have contributed to the declines in catch must be understood if ameliorative/restorative actions are to be implemented in a strategic fashion. These factors may include a combination of both recruitment and water quality issues. Furthermore, ~25% of seagrass was lost from the system between 2005 and 2011, which may also have contributed.

Objectives

1. Examine school prawn recruitment to different areas within the Camden Haven estuary, to determine if recruitment limitation in certain areas is likely
2. Evaluate whether post-recruitment processes in Camden Haven estuary may be adversely affecting school prawn growth and survival
3. Synthesise research findings to provide recommendations to catchment, habitat and fishery managers regarding restoration of school prawn productivity

Final report

ISBN: 978-1-76058-345-3
Authors: Matthew D. Taylor Catherine McLuckie Angela Russell R. Hugh Dunstan Natalie A. Moltschaniwskyj Geoffrey MacFarlane Marcus Crompton Neil R. Loneragan
Final Report • 2019-10-01 • 6.97 MB
2015-011-DLD.pdf

Summary

New South Wales Department of Primary Industries (NSW DPI) presents new information exploring the effect of catchment-derived stressors on Eastern School Prawn. Declines in School Prawn productivity over decadal time scales have been reported anecdotally across many estuaries in New South Wales, and are evident in the catch statistics in some locations. This has included reports that indicate that prawn landings have become decoupled from freshwater flows, which generally enhance catches in estuarine and inshore fisheries. To date, no research has been conducted into the direct effects of environmental conditions within nursery habitats that may be contributing to these changes in productivity. This project commenced this investigation using the Camden Haven estuary as a case study, and through a combination of high-resolution logger data, aquarium experiments, habitat mapping, extensive field sampling, and analysis of commercial catch statistics, provide evidence to link catchment-derived stressors with changes in productivity of School Prawn. We use this evidence to propose recommendations for targeted repair in the Camden Haven estuary catchment, as well as other New South Wales estuaries supporting School Prawn harvest.

Related research

Industry
Environment
PROJECT NUMBER • 2019-079
PROJECT STATUS:
COMPLETED

Knowledge for Productivity: Phase I - Lake Wooloweyah

1. To determine the potential increases in fishery productivity using School Prawn (Metapenaues macleaya) and Eastern King Prawn (Penaeus plebejus) as readily understood community indicators of fisheries productivity
ORGANISATION:
University of Newcastle
People

Understanding recruitment variation (including the collapse) of Saucer Scallop stocks in Western Australia and assessing the feasibility of assisted recovery measures for improved management in a changing environment

Project number: 2015-026
Project Status:
Completed
Budget expenditure: $205,962.00
Principal Investigator: Mervi Kangas
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 30 Jul 2015 - 30 Aug 2016
Contact:
FRDC

Need

The perception that fisheries collapse or recruitment failure is the result of overfishing reflects badly on industry, researchers and managers. It is important therefore to understand the cause of recruitment variation (and failures) and to clearly explain these to stakeholders. In light of recent stock surveys, indicating extremely low levels of recruits and adults, it is likely that natural recovery is now impeded due to insufficient spawning stock to produce successful recruitment even under ideal environmental conditions. Closure of these fisheries has had a major financial impact on the industry. This led to a workshop of scallop experts, industry and managers to discuss the cause of the collapses; whether these conditions are likely to remain and if they will improve to permit some recovery. Due to very low stock abundance it could be that the breeding stock is too low or the survival of larvae/juveniles has been reduced to compromise a significant stock recovery.

An urgent need was identified to understand recruitment variation including the initial stock collapse, investigate the potential of assisted recovery measures (such as restocking) to re-establish founder populations in these extremely depleted stocks, and provide management/industry with a cost-benefit evaluation of these measures to aid recovery. Fishery restoration through assisted recovery has shown some success with Roe’s Abalone in WA and may lend itself as a management tool in a changing marine environment.

Objectives

1. Understanding factors influencing recruitment variations in existing scallop WA stocks, particularly the collapse of the stocks in 2011
2. Determining feasibility of re-establishing founder population of scallops in the Abrolhos Islands and Shark Bay through seeding of hatchery produced juveniles
3. Determining feasibility of re-establishing founder population of scallops in the Abrolhos Islands through translocations

Final report

ISBN: 978-1-921258-63-3
Authors: A. Chandrapavan M.I. Kangas N. Caputi
Final Report • 2020-07-01 • 5.35 MB
2015-026-DLD.pdf

Summary

This study examined possible contributing environmental factors to the recruitment variability of the Ballot’s saucer scallop Ylistrum balloti across the main stocks in Western Australia. The project was undertaken to explain the variation observed between years and between regions as well elucidating the potential cause of a major decline in scallop stocks following an extreme marine heatwave, with these findings intended to improve future management advice.
Secondly this project was to examine the feasibility of using assisted recovery through seeding of hatchery produced juveniles or translocation of mature breeding stock or immature scallops.