Developing innovative approaches to improve CPUE standardisation for Australia's multispecies pelagic longline fisheries

This project was undertaken by a collaboration of senior fishery scientists at CSIRO and from New Zealand, together with a former fisheries manager now with the Commonwealth Department of Agriculture and Water Resources in Canberra, on the development of methods to construct indices of stock abundance trends from commercial catch-per-unit-effort (CPUE) in multispecies pelagic longline fisheries. Such indices are crucial inputs into stock assessments undertaken around the world and play a vital role in achieving the sustainable management of global fisheries. The project work was undertaken during 2015 and 2016, using the multispecies longline fishery for tuna and billfish on the east coast of Australia (the Eastern Tuna and Billfish Fishery) as the example case study. As indices of stock abundance constructed from CPUE data are the central inputs into the harvest strategy used in this fishery to inform the determination of annual Total Allowable Commercial Catch (TACC) limits, there was a need to identify the accuracy of current methods and develop new methods to construct more reliable indices of stock abundance. In this regard, the analyses undertaken during the project and presented here were designed to address specific issues related to this fishery. However, it is also hoped that the general results of this project will have broader applicability to other multispecies species, both domestically and internationally.