Mahi Mahi

• Western Tuna and Billfish fishery (WTBF: 0.8t in 2024)

Mahi mahi is a highly migratory species found throughout all tropical and subtropical ocean basins. They are very fast growing and short-lived, characteristics that provide resilience against overfishing.

Mahi mahi is not specifically targeted by fishers, but is taken as a secondary species in a tuna longline fishery that operates off the Western Australian coast.

The eastern and western mahi mahi populations are poorly understood, but low catches in the WTBF and the fast-moving life cycle of the fish give confidence that populations are healthy.

Mahi mahi are caught using longlines in Australian waters, which also catch a range of threatened species. Independent 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 were significantly under-reporting how much endangered wildlife was killed in the past, which means that the impact of this fishery 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.

Despite this, most current management arrangements for the ecological risks of the fishery to endangered species is based on unreliable information collected before the implementation of cameras, though there is now 10 years of reliable data available to ETBF and WTBF managers. The relatively very low level of fishing activity in the WTBF in recent years significantly reduces the risk that fishery poses to threatened and endangered bycatch species.

Turtles, whales, dolphins and seabirds are at risk from multiple threats, including fishing. Given the small scale of the Western Australian tuna fishery relative to international tuna fisheries, it is unlikely that this fishery is the major driver of on-going population declines in these species of endangered wildlife.

Marine sanctuaries, areas where fishing is not allowed, provide valuable protection to species, allowing for greater confidence in surrounding fisheries.

The Australian tuna fishing industry has extensively lobbied for the removal of marine sanctuary protection in areas where they want to fish. They have been successful on multiple occasions.

Marine sanctuaries are a fundamental part of healthy oceans, and their targeted reduction is not in the best interest of the ocean or the industry. This continued effort to undermine marine sanctuaries is a disappointing lack of environmental stewardship.