Underwater footage reveals the terrible cost of industrial fishing

Industrial fishing is sweeping up unprecedented levels of bycatch, including nearly half a million threatened blue sharks in the Western and Central Pacific Ocean alone, new analysis shows, as the world finalises a new ocean treaty.

The Western and Central Pacific Fisheries Commission’s annual catch estimates suggest that 438,500 blue sharks were caught in 2023, the latest year for which figures are available.

If laid nose to tail in a straight line, the blue sharks would stretch for 900 kilometres, as far as from Sydney to Melbourne and more than the distance of a return trip to the International Space Station.

The blue shark bycatch weighed 48,200 tonnes. Greenpeace analysis of previous reports back to 1991 suggests this is the highest number on record, and more than double the 23,466 metric tonnes caught in 2015.

Greenpeace senior oceans campaigner Georgia Whitaker said the blue shark was now a vulnerable species because of overfishing despite not being a target species.

Blue sharks make up 91 per cent of the bycatch in the Lord Howe Rise and South Tasman Sea.Credit: Getty Images/iStockphoto

“There’s a huge issue of indiscriminate industrial fishing all over the world, but particularly in the Lord Howe Rise and South Tasman Sea region because you’ll get ... vessels throwing out longlines up to 100 kilometres long, with thousands and thousands of baited hooks picking up everything in its course,” Whitaker said.

“Taking out a predator like [blue sharks] has huge implications for the rest of the ocean ecosystem.”

Greenpeace filtered the commission’s observer data on bycatch by latitude and longitude to calculate that blue shark bycatch made up 91 per cent of all bycatch in the Lord Howe and South Tasman region, close to Australia.

Whitaker said longline fishing was the main technique used in the Lord Howe and South Tasman region. Longlining typically targets tuna, marlin and swordfish, but the fishing method has been criticised for not being selective.

Rays, turtles, marine mammals and seabirds are also caught as bycatch. Buller’s albatrosses and shy-type albatrosses were 4 per cent of the Lord Howe and South Tasman bycatch.

A sea turtle pulled up on a longline by a Taiwanese-flagged ship in the North Pacific in 2024.

Another industrial fishing technique is bottom trawling, where a heavy net is dragged along the ocean floor to catch fish and crustaceans, especially species that live on or near the seabed.

This is highlighted in the new David Attenborough documentary Ocean, in Australian cinemas now, which has some of the first high-resolution vision of bottom trawling.

Filmmakers Toby Nowlan, Keith Scholey and Colin Butfield said in a joint statement that the footage was shot in two parts, including as part of a scientific study with the Marine Biological Association, and on board a working trawler, with the cooperation of the Turkish government.

The Western and Central Pacific covers 20 per cent of the Earth’s surface, stretching from the Great Australian Bight around the east coast of Australia, up to Japan, and east to waters north of Hawaii.

The United Global Oceans Treaty, also called the High Seas Biodiversity Treaty, was agreed two years ago and 115 countries have signed it so far. Only 21 countries have ratified it – or passed it into domestic law – and 60 are needed before it comes into effect.

Australia was one of the first signatories. A spokesperson for Environment Minister Murray Watt said Australia was in the process of ratifying the treaty, which required legislation.

The minister was considering the invitation to attend the UN Oceans Conference in Nice, France, next month and would make a decision soon.

“Australia’s priorities for the UN Ocean Conference will include sharing our sustainable ocean management experience (including marine protected areas), learning from others and advocating for the priorities of Pacific Island countries,” the spokesperson said.

There are already marine protections in Australia’s territorial waters around Lord Howe Rise, but Greenpeace is lobbying for Australia to push for international protection under the treaty.

Watt’s spokesperson said the Australian government co-hosted a research symposium on the Lord Howe Rise and South Tasman Sea in early May 2025 and would consider next steps for a potential high seas marine-protected area proposal in this location in partnership with other countries.

Peak body Seafood Industry Australia said in a statement that bottom trawling practices were in urgent need of reform in some parts of the world, but Australia was different.

Trawling in Australian waters was highly regulated, occurring on 1.1 per cent of the nation’s 8.2 million km² marine estate and avoiding sensitive areas such as reefs and seagrasses, the statement said.

Seafood Industry Australia chief executive Veronica Papacosta defended longlining.

“It’s ludicrous to suggest that longline fishing is not selective,” she said. “It is one of the most sustainable fishing practices in the world.”

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