Project number: 2009-012
Project Status:
Completed
Budget expenditure: $191,550.47
Principal Investigator: Jessica H. Farley
Organisation: CSIRO Oceans and Atmosphere Hobart
Project start/end date: 30 Jun 2009 - 29 Jun 2011
Contact:
FRDC
SPECIES

Need

In 2005, the Ministerial Directive to AFMA included the requirement to develop harvest strategies for all Commonwealth fisheries. To determine target reference points for albacore in the ETBF consistent with the Harvest Strategy Policy, data are required on several biological parameters such as size/age-at-maturity, growth rates, fecundity and mortality (Campbell et al., 2007). Furthermore, to estimate spawner-per-recruit reference points which are used as proxies for MSY-based reference points, the agreed harvest strategy for the ETBF specifically requires estimates of size-at-maturity and mortality. However, the harvest strategy currently uses life-history parameters taken from SPC’s regional stock assessment, which in turn are either uncertain or assumed (Hoyle, 2008). For example, growth parameters are based on less reliable length-frequency and vertebrae ring counts, and the maturity schedule is based on a study of North Pacific albacore from the 1950s. There are no reliable estimates of fecundity or spawning frequency for any albacore stock. Thus, the WCPFC-SC has identified the need to improve our understanding of life-history parameters and stock assessment for albacore as a high priority.

In 2008, the stock assessment model for South Pacific albacore was revised and "the cumulative effect of these changes was to reduce the biomass estimates and raise the fishing mortality estimates compared to previous assessments" (Hoyle et al., 2008). Although there is still significant uncertainty in the model, the assessment provided a more pessimistic view of stock size and MSY (1/3 of the volume) compared to the 2006 assessments. Such a significant change highlights the requirement for accurate assessments of albacore and the ensuing need for revised biological data.

In 2008, the ETMAC called for research to determine biological characters of albacore as a priority project (project-7). The current proposal addresses this need and will maximize the value of complimentary studies being undertaken at SPC.

Objectives

1. Collect biological samples (otoliths, spines, gonads & muscle) from albacore caught in the southwest Pacific in cooperation with AFMA, SPC and MFish using the sub-sampling regime designed in the tactical project.
2. Determine length-weight conversion factors for albacore in the ETBF
3. Depending on successful age validation, determine the age of 2000 albacore and investigate age-related stock parameters including catch-at-age and regional/sexual differentiation in growth
4. Determine reproductive-based stock parameters for South Pacific albacore including sex ratio statistics, maturity schedule(s), spawning fraction and batch fecundity (by size/age) using macroscopic and modern histological techniques
5. Provide key population biological parameters on age, growth, maturity and fecundity to harvest strategy and stock assessment scientists

Final report

Related research

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PROJECT NUMBER • 2017-098
PROJECT STATUS:
COMPLETED

Southern Bluefin Tuna: Changing The Trajectory

1. To inform the recreational fishing sector and general public of the history and current status of SBT, including the role of science
ORGANISATION:
Australian Fisheries Management Authority (AFMA)