Determination of patagonian toothfish age, growth and population characteristics based on otoliths

Funded Activity Summary

Data on fish age are essential to determine the production of fish stocks. Collection of age structure data early in the history of a fishery are particularly important to determine the natural mortality rate of a population. Data relating to the age structure of populations and growth rates can also be applied to the identification of stocks. Annual estimates of population age structure are employed to identify population responses to exploitation and environmental variability and can be used to develop more data intensive methods of population assessment (eg Virtual Population Analysis). Otoliths are the structures employed most often to estimate age of fishes and validation research at the ANU indicates that toothfish otoliths are suitable for this purpose.

A "stock" is the basic unit of management in most fisheries and identification of these units is a prerequisite to accurate assessment and effective management. There are no data on stock structure for Patagonian toothfish. As a result, we have no knowledge regarding the potential impacts of toothfish exploitation outside the AFZ on toothfish stocks within the AFZ.

Knowledge of toothfish biology is extremely limited. Given the lack of baseline biological data, it would be difficult to identify possible responses of toothfish stocks to exploitation or differences in life history characteristics among putative stocks. Identification of changes in basic life history characteristics such as age or size at maturity and timing of ontogenetic migrations are important to management of fish species within both a stock and ecosystem context.

Objectives:
1. Validate otolith-based age estimates for Patagonian toothfish (Dissostichus eleginoides).
2. Establish routine age estimation procedures for Patagonian toothfish.
3. Determine growth rates for Patagonian toothfish.
4. Determine age structure of the toothfish populations from the AFZ surrounding Macquarie Island and other localities
5. Determine age structure from successive years of sampling to identify possible shifts in age structure or inconsistencies in the application of the age estimation method.
6. Liaise with groups involved with modelling the dynamics of toothfish populations.
7. Apply otolith morphometrics and otolith chemistry to discrimination of possible toothfish stocks.
8. Establish an inter-agency (international) program to determine if there is variation in the interpretation of toothfish otolith sections
9. Publish reports for immediate stock assessment and management purposes and peer-reviewed articles in international journals for dissemination of results.

Funded Activity Details

Start Date: 30-06-1997

End Date: 03-05-2001

Funding Scheme: Funding Scheme not available

Funding Amount: $22,850.00

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

Ageing | Animal Health | Biology | Life History | Mortality | Otolith | Stock Assessment

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