Striped Marlin


Latin name: Tetrapturus audax


Common name: Marlin

  • Say No

Wild Caught

Region:
Eastern Commonwealth waters

Key Facts

  • Striped marlin is a migratory species caught by a number of different countries, including Australia, where the main fishery operates along the eastern coastline.
  • Stock status information indicates significant concern over the stock fished in Australian waters, with evidence of high fishing activity and stock declines over a period of decades.
  • The stock fished by Australia is currently overfished, and as fishing pressure is set too high, overfishing will continue to drive the decline in the stock.
  • Video monitoring of all fishing boats operating in the tuna fishery is a welcome advance, improving confidence in fishery log book reports.
  • Striped marlin are caught on longlines that also catch endangered wildlife, such as turtles, seabirds, whales and dolphins.
  • Reported interactions with turtles, seabirds, whales and dolphins have increased significantly in recent years, most likely as a result of the introduction of video monitoring in this fishery.
  • The number of threatened and protected wildlife caught in the fishery is of increasing concern, and fishery managers would need to put wildlife protection measures in place to retain an Amber rating in future.

More information

  • Commonwealth Eastern Tuna and Billfish Fishery (276t in 2017-18)

Striped marlin is found in the Pacific and Indian Oceans and caught throughout its range by fisheries managed by other nations, including Australia, Taiwan, Japan and the Republic of Korea. The majority of striped marlin is caught in the tuna fishery off the eastern coastline of Australia, with a small (less than 1t) catch from the western coastline that is not covered by this assessment. There are no reports from trade data that show striped marlin is imported into Australia, hence the assessment and ranking is the result of an assessment of the major Australian fishery.

Striped marlin is caught in a fishery that mainly targets tuna. Stock status information indicates significant concern over the stock of striped marlin, with evidence of high fishing activity and stock declines over a period of decades. The stock fished by Australia is currently overfished, and as fishing pressure is set too high, overfishing will continue to drive the decline in the stock.

Management actions imposed by regional authorities that manage the stocks shared by a number of fishing nations have not been authoritative, and stocks in some regions are continuing to decline.

Striped marlin 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 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.

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 turtle catch 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 killed in 2017 after camera installation. Similarly, no dolphin or whale deaths were reported in 2013 or 2014, but 7 dolphins and whales were 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 on-going population declines in these species of endangered wildlife. As the framework that is in place to manage the fishery is robust, 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 fishery reporting. However, fishery managers would need to put wildlife protection measures in place to reduce the impact of fishing on these species in order to maintain an Amber ‘ Think Twice’ rating in future.

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 area protected from fishing in offshore eastern Australian waters.