In 1982, CSIRO applied to the Fishing Industry Research Trust Account for funding of a joint biological investigation of northern Australian pelagic fish stocks. At that time these stocks supported a Taiwanese surface gill-net fishery based on sharks, tunas and Spanish mackerel.
During the 1970's the total annual catch taken by the Taiwanese fishery from the area between northern Australia and Papua New Guinea averaged about 25,000 tonnes live weight. With declaration of the Australian Fishing Zone (AFZ) in 1979 the fishery came under Australian jurisdiction and management measures were introduced. Simple yield estimating procedures based on the commercial catch data were used to derive an annual quota of 7,000 tonnes processed weight (about 10,000 tonnes live weight). The quota was assumed to be set at a conservative level of the potential yield. However, the only information available on the stocks at this time was some limited data on species composition together with preliminary data on size and sex distributions and reproduction of some of the shark species obtained by sampling the commercial catch through the AFZ observer program. Little information was available from inshore waters not fished by the Taiwanese and nothing was known about stock structure or the population dynamics of the main species that would allow a more scientifically defensible position to be adopted on the existing exploitation rate.
This study was initiated because of mounting government concern over the lack of research into the fishery, and because of increasing interest by industry in Australian exploitation of the resource. The program was a joint undertaking between CSIRO, the Commonwealth Department of Primary Industry and the State Fisheries of Queensland, Western Australia and the Northern Territory. The program aimed to provide information on the stock structure, migration, age and growth, recruitment and mortality of the principal species, and to examine the yield potential of the stocks and the potential for increased Australian participation in the fishery. It was particularly important to know whether the target species comprised single stocks or a number of discrete stocks across northern Australia. This information has implications for management of the foreign and domestic fisheries.