The five target species of the Australian east coast longline fishery (albacore, bigeye, yellowfin tuna, striped marlin, broadbill swordfish) have a wide distribution outside the Australian EEZ. The abundance and distribution and hence availability of these highly migratory tuna and billfish species to fisheries are known to be strongly influenced by oceanographic conditions (e.g. currents, temperature, salinity and oxygen). The waters off the east coast of Australia are also experiencing rapid climate change, with range expansion already observed for many coastal and pelagic fish species. Changes in distribution over the 21st century are also projected for these five species in eastern Australia and the wider Pacific.
We show the application of a selection of different modeling techniques to explore tuna availability in now-cast, and where possible, forecast, mode for the Eastern Tuna and Billfish Fishery in Australia. We have leveraged the CSIRO Decadal Climate Forecasting Project (DCFP) 60 year (1960-2019) coupled ocean-atmospheric reanalysis, CAFE60, and the Australian Community Climate & Earth System Simulator – Seasonal, ACCESS-S, to explore links between basin and regional-scale Pacific Ocean variability and western pacific fisheries. Connectivity of stocks between the Australian EEZ and the western pacific means that environmental signals in one region may influence the distribution, size, and abundance of target species in another. A better understanding of the large-scale ocean variability in the Tasman Sea and Western Central Pacific may lead to new insight that could improve predictions of likely fishery conditions in the future.