Budget expenditure: $541,804.00
Project Status:
Current
Principal Investigator: Anthony J. Fowler
Organisation: University of Adelaide
Project start/end date: 19 Jan 2020 - 30 Dec 2022
Contact:
FRDC
TAGS
Survey
Stock Assessment
Resource Access And Allocation
Reproduction
Population Dynamics
SPECIES
Snapper

Need

The population dynamics and fishable biomass of Snapper in South Australia are fundamentally driven by high inter-annual variation in recruitment, i.e. the numbers of 0+ juveniles that recruit to populations. Throughout the 2000s, SA’s Snapper stocks experienced different trends in recruitment that led to extraordinarily different trends in fishery catches. For the Spencer Gulf/West Coast Stock successive poor year classes led to the significant decline in fishable biomass, and a ‘depleted’ stock status. In contrast, the Gulf St. Vincent Stock increased to unprecedented levels due to numerous strong recruitment year classes, but since 2015 has also experienced considerable declines in fishery catches. In 2019 it was classified as ‘depleting’. From 2018, concerns about both stocks prompted a comprehensive review of the fishery management approach. This resulted in significant changes to the management strategy including a spatial and long-term fishery closure. Despite this, there remains the need to monitor the stocks and demographic processes. Given the significance of variable recruitment for Snapper, the need for regional, annual estimates of recruitment as an indicator of future trends in fishable biomass has re-emerged. Between 2000 and 2010, recruitment surveys were done in Northern Spencer Gulf, for which the sampling methodology, i.e. otter trawling, was non-selective and destructive of benthic and demersal biota. One need here is to develop a cost-effective, non-destructive sampling strategy for future annual sampling. Also, there is the need to develop a better understanding of larval ecology, connectivity, and the causes of variable recruitment. Combined benefits from addressing both needs would significantly enhance predicting future trends in fishable biomass.

Objectives

1. To develop our understanding of the processes that regulate recruitment based on finalising datasets from previous research projects that relate to the early life history, and larval and juvenile ecology of Snapper, as well as the annual variation in environmental factors
2. To undertake an empirical study to compare the utility and effectiveness of several potential sampling methodologies to provide a relative recruitment index for Snapper and to develop a sampling strategy for future surveys
3. To apply the sampling strategy as developed in Objective 2 in the following two years, to provide relative estimates of the recruitment rates for Snapper in NSG and NGSV

Related research

Adoption
Industry
Blank
PROJECT NUMBER • 2019-085
PROJECT STATUS:
CURRENT

National Snapper Workshop - Rebuilding our iconic Snapper stocks

1. To identify key issues and challenges for Snapper, review Snapper research, and critique jurisdictional management arrangements.
ORGANISATION:
Department of Primary Industries and Regions South Australia (PIRSA)