This project should prove to be a demonstration of how the judicious use of research and analysis can improve performance against the policy (CHSP).

Current assessments indicate that Bmsy for Bight redfish and deepwater flathead are 24% and 27% Bzero respectively. Applying the default Bmey = 1.2 Bmsy (as used in the Commonwealth and SESSF harvest strategy policy) would give target biomass levels of B28 and B32 respectively. These figures are uncertain due to an assumed stock recruitment relationship in the assessments and apparently cannot be used to estimate BMEY. As a result, the precautionary default B48 target is being used for both species. This is potentially resulting in many hundreds of tonnes loss to the fishery each year and the fishery operating at sub-optimal economic conditions.

There is an urgent need for estimates of Maximum Economic Yield (MEY) and fleet structure and efficiency in the GAB, to build on the proven sustainability, but also to ensure that profitability and efficiency targets are met as per the CHSP. This project has two components:

(1) Pursuing the CHSP through the calculation of MEY by incorporating economic information and calculations with fishery catch and effort information fitted to and projected by the existing biological stock assessment (built and maintained by CSIRO since 2006). A model that determines maximum economic yield requires a model structure that can iterate both the biological assessment and projections and also the economic calculations, and measures of profitability.

(2) Measures of efficiency to determine fleet structure and optimal combinations of inputs. An MEY target determines the most profitable level of overall catch but does not indicate the optimal number of fishing vessels and input configurations needed to secure that harvest. An MEY target combined with efficiency measures ensures profitability and maximum efficiency.

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.