The proposed project addresses a number of areas recognised as high priorities within the ET&BF Research Plan and has been rated as the highest priority project within the 1998 Eastern Tuna MAC priority setting process.
In the ET&BF there are both regional and local-scale questions that must be addressed before an operational model can be used to develop harvest strategies for east coast bigeye. The project addresses a number of these key questions:
1. In a climate of rapidly increasing effort on bigeye within the ET&BF, concern over the sustainability of bigeye resources in the EPO and W/CPO, and the development of a management plan and harvest strategy for bigeye in the eastern AFZ, it is essential that we understand the stock structure of bigeye in our region. Bigeye stock structure has been listed as Priority 1 in the ET&BF Research Priorities. The proposed project, in combination with similar and collaborating projects in other parts of the Pacific Ocean seeks to define links between bigeye populations throughout the Pacific.
2. Assessments of the sustainability of bigeye populations in the AFZ and in the broader Pacific urgently require more information on the behaviour and habitat preferences of bigeye (Hampton 1998). Assessment of historical and current catch data in the ET&BF and surrounding region is Priority 2 in the ET&BF Research Priorities. The proposed project is designed to collect data that will allow objective analysis of bigeye CPUE trends through incorporation of information on habitat preferences, and variation in these on seasonal and annual time scales.
3. The interpretation of tagging data from the Coral Sea, used by Hampton and Gunn (1998) to estimate exploitation rates of bigeye in this area, requires additional information on the habitat preferences and seasonal migration patterns of bigeye in the Coral Sea/Tasman Sea basin. Determining the links between bigeye fisheries in Area E and those on the SE Queensland/Nth NSW coasts is also essential in interpretation of the tagging data and understanding the likely impacts of increased effort in different areas of the ET&BF : Priorities 5, 7 and 8 of the ET&BF Research Priorities.
4. The strontium marking of conventionally tagged fish will provide material for the validation of age estimates produced by CSIRO’s FRDC Pilot Project developing and assessing methods to age bigeye : Priority 5 in the ET&BF Research Priorities.
In addition (and perhaps in competition) to the fisheries management issues, a significant spin-off from the proposed project will be a quantum leap in our understanding of the behaviour and seasonal movement of bigeye in the eastern AFZ (and broader Pacific). These advances will allow fishermen to more effectively and efficiently target bigeye in the future.
