Latin names: Thunnus obesus
Common Names: Tuna
Wild Caught - Australian and Imported
- Commonwealth Eastern Tuna and Billfish Fishery (433t in 2017-18)
- Commonwealth Western Tuna and Billfish Fishery (95t in 2016)
- Imported from Indian Ocean, Western & Central Pacific Ocean fisheries
Bigeye tuna is a highly migratory species of tuna that is targeted by fishing vessels managed by a number of different countries. Due to high demand for bigeye tuna, fishing pressure on the species is intense. Bigeye tuna is listed as 'Vulnerable' to extinction on the IUCN Red List.
Fishery reports that have assessed the stock status of the species at a regional level previously indicated that stocks in all areas where bigeye tuna are caught were depleted beyond sustainable levels. More recent assessments suggest the stocks fished by Australian fishing fleets on the eastern and western coasts are healthier than previously thought, although there is some uncertainty as to the robustness of this new information. A precautionary red rating is retained for all bigeye tuna as recent decisions to increase the overall catch of bigeye tuna is against scientific advice and is of concern. Overall international management of bigeye tuna in these regions requires considerable improvement.
Australian fisheries target bigeye tuna along the eastern and western coasts. The stocks targeted are the same stocks as those caught in other fisheries in the Pacific and Indian Oceans.
Bigeye tuna are caught using longlines in Australian waters, which also catch a range of threatened species. In previous years, fishery observers undertook independent monitoring of the impact of fishing on endangered wildlife. Video monitoring across the fishing fleet was rolled out in 2015. This welcome progress provides confidence in reporting of wildlife affected by the fishery.
However, video monitoring has identified that fishers in the eastern and western fisheries were significantly under-reporting how much endangered wildlife was killed in the past, which means that the impact of these fisheries is substantially higher than previously thought. Since cameras have been installed on boats, the number of turtles, seabirds, whales and dolphins recorded as caught has significantly increased.
In the larger eastern fishery, the catch of turtles in particular has increased over the past decade. In 2017, 194 turtles were caught, compared to the 4-16 that were reported as caught annually in the three years before video monitoring was mandated on the fishing vessels. In previous years, a ‘trigger limit’ was in place which required fishery managers to take action if the rate of turtles caught exceeded a certain level. This trigger limit has since been removed, which means there are no measures in place to cap the number of turtles caught in the tuna fishery.
A similar picture has emerged in seabird and marine mammal bycatch. There were zero seabirds recorded in log-books in 2013, before video cameras were installed, but 34 seabirds were killed in 2017 after camera installation. Similarly, no dolphin or whale deaths were reported in 2013 or 2014, but 7 dolphins and whales were reported killed in 2017.
Turtles, whales, dolphins and seabirds are at risk from multiple threats, including fishing. Given the small scale of the Australian tuna fishery relative to international tuna fisheries, it is unlikely that this fishery is the major driver of ongoing population declines in these endangered wildlife species. The framework in place to manage the fishery is robust, so it is expected the identification of these issues will lead to improvements in the fishery. Increased monitoring of the fishery is a significant improvement, leading to greater transparency and more reliable reporting, however, fishery managers need to put wildlife protection measures in place to reduce the impact of fishing on these species.
Commonwealth marine parks, set to be established in 2018, may provide a degree of protection to endangered wildlife. However, it is notable that sectors of the tuna fishing industry sought, and may yet secure, significant reductions in the areas protected from fishing in offshore eastern and western Australian waters.
Bigeye tuna caught in the Pacific and Indian Oceans is taken using longlines, gillnets and purse seines associated with Fish Aggregating Devices (FADs). FADs are artificial objects that float on the surface of the ocean, which exploit the natural tendency of fish and other marine wildlife to aggregate under floating objects. The bycatch of large numbers of sharks, including whale sharks, and turtles has been well documented in FAD associated fisheries. Longlining and gillnetting is also responsible for the capture of threatened sharks, turtles and seabirds.
The countries that manage the fisheries generally do not monitor the bycatch caught, and independent observer coverage is low to non-existent.