Regrowth of pilchard (Sardinops sagax) stocks off southern WA following the mass mortality event of 1998/1999

Funded Activity Summary

There is a need to assess the regrowth of pilchard stocks in southern Australia because of (1) the socioeconomic problems associated with fishery declines and the associated need to provide sufficiently detailed information so that management can proceed with the appropriate balance between sustaining the fishery and allowing recovery of the stocks, and (2) the potential for causes of wide ranging ecosystem affects to go unrecognized if there is no baseline data (i.e. abundance) for this key pelagic species.

In order to provide a time-series of the regrowth of S. sagax stocks in WA the biomass size of each adult assemblage needs to be assessed over the next few years. Because the ecosystem-based goal of this project is to provide a baseline of pilchard abundance which may relate to other species, the longer life spans, slower growth etc. typical of these higher trophic levels necessitates a long time series of surveys. Changes in biomass of the four pilchard assemblages should be assessed for a period of at least five years. Although this is a relatively short period of time over which to examine the recovery of a pelagic stock, such a routine will provide a solid basis for assessing the rebuild of pilchard abundance and thereby pro-actively collect data which could subsequently assist our understanding of other ecosystem affects of the Herpesvirus mortality event. This project will compliment the annual DEPM surveys intended for SA pilchard stock.

Collection of a continuous, albeit short-term, series of estimates of spawning biomass will permit the age structured simulation model being developed by Hall and Gaughan (in prep.) to be fitted to a likewise continuous series of these estimates. This should improve the fitting of the model, thereby making it more useful for predicting impacts of further mortality events involving S. sagax in southern Australia and facilitating the decision -making process in the ongoing management of pilchards in WA.

Objectives:
1. Document changes in the biomass of the four exploited adult assemblages of S. sagax in WA during the six year period following the 1998/99 mass mortality event.
2. Integrate results of biomass surveys into the age structured model for each assemblage of pilchards. Further develop the age-structured simulation models for S. sagax and investigate ongoing behaviour of these under conditions of different levels of information
3. Determine if there is a measurable change in biological parameters of pilchards important to ongoing development of the simulation models, in particular growth rate, in response to the decrease in stock size.

Funded Activity Details

Start Date: 10-10-2000

End Date: 31-07-2008

Funding Scheme: Funding Scheme not available

Funding Amount: $508,065.00

Funder: Fisheries Research and Development Corporation

Research Topics

ANZSRC Field of Research (FoR)

There are no FoR codes available for this funding activity

ANZSRC Socio-Economic Objective (SEO)

There are no SEO codes available for this funding activity

Other Keywords

Biomass | Ecosystem | Mortality | Social Science | Stock Assessment

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