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Longline Fishing Threatens Seabirds and Other Marine Life

Seabirds, sea turtles, and other ocean dwellers are killed bylongline fishing

The Humane Society of the United States

Longline fishing is the commercial fishing industry’s version of traditional hook and line fishing—only far more indiscriminate and deadly. Ocean vessels trail a main fishing line up to 60 miles (about 100 kilometers) long, with secondary lines branching off of it that have thousands of barbed, baited hooks. A total of almost two billion such hooks are used each year, according to The PEW Charitable Trusts. Longliners usually target large fish such as tuna, swordfish and Patagonian toothfish (Chilean sea bass), but the baited hooks also attract and result in the deaths or bycatch of a wide variety of other animals, including sea turtles, marine mammals, seabirds and non-target fish, in what amounts to a mass slaughter at sea. Some estimates claim that longlines kill more than 40,000 sea turtles, 300,000 seabirds, thousands of marine mammals and millions of sharks each year.


Sea turtles are among the endangered victims of the longline. Attracted to the bait used on longline hooks, turtles die slowly from swallowing them. They may also be severely injured by a hook in the mouth or by a hook that snags their flippers as they swim near the gear. Turtles can get entangled in the lines. They can drown if a large fish near them bites a hook and drags the line down so that the turtle cannot surface for air. The leatherback sea turtle is especially vulnerable to this fishing method, in part because the light sticks used to attract fish look like jellyfish, their favorite food.

A new type of hook called a circle hook has been shown in some studies to be less deadly to sea turtles than the commonly used "J" hooks. Fishers can also be taught the safest way to remove a hook from a sea turtle and how to resuscitate a comatose sea turtle. 

The HSUS and Humane Society International are working with regional and international policy makers such as the Inter-American Convention on the Protection and Conservation of Sea Turtles to increase protection from commercial fisheries for sea turtles. 

Marine mammals

Sperm whales, oceanic dolphins, pilot whales and orcas are also attracted to the bait on longline hooks or to the fish caught on the hooks. Dolphins and pilot whales swallow hooks or suffer injury or drown if they become entangled in the longlines or the individual lines (called gangions) hanging from the mainline. Even if the lines are cut, the injured animals often swim off to die. Hundreds perish each year in the U.S.; thousands worldwide.

The HSUS works closely with the U.S. government and commercial fishing industry to address these problems. Seasonal restrictions are the best available solution, though they face strong resistance from the fishing industry.


Longline fishing also provides a tempting but deadly source of food for seabirds, such as endangered albatrosses and petrels. The birds get caught in fishing lines and drown or receive mortal wounds from hooks when they go after the bait. Hundreds of albatross die this way each week.

There are techniques available that limit the threat to seabirds, including setting the hooks deeper than seabirds can dive, using streamers called “tori lines” to scare birds away, and fishing at night since birds feed during the day.

Humane Society International and our Australian office are fighting the illegal fishing of Patagonian toothfish (often marketed as Chilean sea bass) in the southern oceans, which results in the deaths of hundreds of thousands of seabirds and has caused a decline in vulnerable Patagonian toothfish populations.

We also work closely with international fishing and environmental agreements including the Agreement on the Conservation of Albatrosses and Petrels (ACAP), and our Australian office is a member of the Threat Abatement Team in Australia.


Longliners are the worst culprits when it comes to shark finning.

This fishing technique is very effective for catching sharks and indeed, many longline vessels are specifically fishing for sharks. However, some that catch sharks will cut off their fins and then throw the animals back in the water, leaving them to bleed to death. Shark fins can fetch a very high price due to the demand for Asian shark fin soup. Enforcing a requirement to bring in the whole bodies of these large animals would allow boats less space for the targeted species.

Recently, countries have started to adopt laws and international agreements against this cruel and wasteful practice; yet it is still legal in many places and laws against it are too lenient and poorly enforced.

Humane Society International is campaigning to strengthen domestic and international laws against and reduce demand for shark fins.

What you can do to help

Call on major fishing countries with large longline fleets, including the United States, the European Union (especially Spain), Japan and China to implement and enforce stricter measures to reduce fishing efforts, combat illegal fishing, and protect non-target species. Write to the agency or ministry that addresses fishing and the ministry that addresses environmental issues. The best solution would be to significantly reduce overall fishing efforts and implement international regulations to require longliners to avoid certain sensitive areas and times. 

The global commercial fishing industry earns billions of dollars a year and has considerable political influence. Most people are unaware of how much animal suffering, conservation and ecosystem damage it does as it takes place on the high seas, far from the public eye. Let governments know that you are concerned and urge them to take appropriate action!

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