There are numerous Australian jurisdictions that have faced and are currently facing management challenges with Snapper stocks in decline. It proposed that a national Snapper workshop is needed to bring together from each jurisdiction fisheries managers, scientists and key stakeholders from the commercial and recreational fishing sectors to:
(1) Communicate findings on Snapper research, gain an insight into the challenges, successes and learnings from management arrangements implemented in each jurisdiction.
(2) Identify a national approach to collaborate and manage a Snapper stock that crosses jurisdictional boundaries
(3) Develop a set of national R&D priorities for Snapper, in particular dealing with the issue of ‘hyperstability’.
(4) Develop a tool kit to support fisheries managers recover Snapper stocks.
The main aim of the workshop is for each jurisdiction to exchange information on Snapper and to ensure that Snapper R&D has a national co-ordinated approach that addresses the challenges being faced, makes the most efficient use of available resources and integrates key stakeholders such as the recreational and commercial fisheries, government and research providers.
A better understanding of the impacts of environmental drivers on the population dynamics and abundance of key fishery species can inform flexible management decisions that pre-empt both risks of overfishing under adverse environmental conditions and opportunities for increased harvest under favourable conditions. This is increasingly important as shifting environmental dynamics drive geographical shifts in fish stocks.
This project will identify environmental variables influencing the abundance of three priority fishery species, quantify those relationships to enhance their stock assessment models, and develop a forward projection tool to inform adaptive management of each fishery. Target species - Spanner Crabs, Snapper and Pearl Perch – were selected based on key interest to management of fisheries in Queensland and NSW. Some associations between these species and certain abiotic environmental factors are already known, but there is yet to be a rigorous and comprehensive approach to this work, with the explicit goal of incorporating abiotic influences into Queensland and NSW stock assessments.
The project has three key objectives: (1) Find indices of association between measures of abundance and key environmental drivers; (2) Use these indices to enhance the existing stock assessment model for each species; and (3) Enable forecasting of environmentally driven fluctuations in targeted species’ abundance, including enhancing Management Strategy Evaluations (MSEs).
In particular, environmental correlates will be valuable to fisheries managers by: (a) reducing the uncertainty in biomass estimates, (b) explaining fluctuations in abundance, and (c) characterising what is a “bad year” for each species. Such information can be incorporated into MSEs.
The “Queensland Sustainable Fisheries Strategy 2017-2027” identifies several challenges to fulfilling its mission of ensuring the sustainability of fisheries and the economic viability of fishing sectors. The first of these is “gaps in monitoring and research, which limit the ability to make timely, evidence-based decisions”. This project will close some of these gaps and assist in formulating measures for promoting stock recovery and adaptive management.
This project studied environmental factors which may be influencing the recruitment, catchability or productivity of Snapper, Pearl Perch, and Spanner Crab stocks in Queensland. Two environmental variables: GSLA and Chl-a were found to have strong associations with either abundance or catchability across the three target species. These associations occurred at spatio-temporal scales relevant to each species’ biology. A third variable, SST, also had strong associations with Snapper.
Importantly, all three of these environment variables, GSLA, SST and Chl-a were found to have certain consistent long-term trends, with rates of change depending somewhat on the region under consideration. We demonstrated that incorporating these environmental variables into simple surplus production stock assessment models results, under some scenarios, in delays in stock recovery. This assumed that the above trends of GSLA, SST and Chl-a are sustained and the direction and strength of the identified associations are maintained.
Ensuring that connectivity and stock dynamics are well understood is crucial to determining the appropriate scale for fisheries management and assessment.
There is strong industry and management interest in determining the extent to which connectivity and stock dynamics of snapper along the west coast might have changed over time reflecting changes in environmental conditions and stock abundance.
There is a need to reassess the most appropriate scale for management of the snapper resource in WA under the new Aquatic Resources and Management Act.
There is a need to evaluate whether active-acoustic methods can improve capacity to monitor the spatial distribution and abundance of snapper in key spawning aggregations and whether these methods are complementary to the existing approaches used to assess snapper stocks in the GCB and WCB and elsewhere in Australia.
This report describes a collaborative project focused on Snapper (Chrysophrys auratus) carried out between 2018 and 2021 by researchers from the Western Australian Department of Primary Industries and Regional Development (DPIRD), Flinders University, University of Adelaide, University of Western Australia, and CSIRO. The project was co-funded by the Fisheries Research and Development Corporation and had three key aims, which were motivated by questions raised by commercial fishers in the Gascoyne and West Coast bioregions of Western Australia, about C. auratus stock structure in relation to current fishery management boundaries and the methodologies used to assess these Snapper stocks.
Firstly, the biological connectivity of C. auratus in waters offshore of Shark Bay (in the Gascoyne Coast Bioregion) and to the south off an area between Kalbarri and Geraldton (in the West Coast Bioregion) were investigated using population genomics, otolith chemistry and larval dispersal modelling. These studies identified, for the first time, nursery grounds inside Shark Bay that are attributable to the Gascoyne oceanic Snapper stock, confirmed the larval transport pathways linking these with known spawning grounds around islands off Shark Bay and commenced the development of a recruitment index for this stock.
Secondly, a novel fishery-independent survey method, combining acoustics (sonar) with underwater cameras, termed acouptics, was trialled for monitoring C. auratus stocks off Shark Bay. The study has shown that these active acoustic methods can be used to monitor Snapper aggregations and estimate numbers of fish/biomass, providing a potential addition to the future Snapper assessment toolkit.
Thirdly, this project explored if there had been any changes in the biological characteristics of C. auratus in oceanic waters of the Gascoyne Coast Bioregion and northern West Coast Bioregion over the past 30 years. The study demonstrated changes in maturity of Snapper in the Gascoyne, with the updated parameters used to inform the most recent (2022) assessment of this C. auratus stock.
The outcomes of this project will provide the basis for a review of stock assessment approaches and management arrangements for C. auratus on the West coast of Australia. Outcomes of the acouptics work provides a conceptual basis for application in C. auratus assessment research elsewhere in Australia and New Zealand.
