How new fishing tech can reduce bycatch of turtles and other creatures
Our oceans are full of sophisticated, perfect traps: Nets, hooks, fishing lines. Designed to capture animals destined for our dinner tables, they often catch other wildlife too.
This accidental harvest is known as bycatch, and every year it causes the death of millions of marine animals, including whales, dolphins, sharks, turtles and seabirds. Nets and gear can asphyxiate animals or cause fatal injuries; even when the animals are tossed back to sea, they frequently die. Bycatch is also a dilemma for fishermen - entangled creatures can destroy equipment, costing time, money and fisheries' reputations.
Over the decades, conservationists, researchers and fishermen have developed ways to minimize various kinds of bycatch in different fishing stocks around the world. But putting these solutions to work is often a challenge, and many mitigation strategies are never widely implemented, Knowable Magazine reports.
Pingers and plastic bottles
Another bycatch prevention method that's demonstrated some success is pingers - devices attached to the fishing gear that emit sounds that deter echolocating whales and dolphins. A field trial of the devices in three Norwegian fisheries using gillnets, for example, showed that pingers reduced bycatch of harbor porpoise by 94%, a team reported in "Fisheries Research" in 2023.
But pingers can have their downsides. An analysis of pinger effectiveness in waters off the United Kingdom, where they have been used for more than a decade, found that while they were linked to a reduction in bycatch of porpoises, they were also linked with an increase in bycatch of seals, which seem to associate the sound with a potential meal. "It's like a dinner-bell effect," says policy specialist Sarah Dolman of the Environmental Investigation Agency, a London-based nonprofit that campaigns for environmental issues.
Pingers that transmit at frequencies outside of pinnipeds' hearing range and are thus considered "seal-safe" have been developed. But the devices can also be expensive, especially for artisanal fishermen, who tend to use lower-tech gear and may lack supportive government policies and investments.
Some of those small-scale fisheries may reduce bycatch of echolocating animals with a low-tech approach: fixing plastic water bottles to their nets. Detecting thin, fine nets is difficult for dolphins, porpoises and other echolocators, but water bottles are a more easily detectable obstacle that could help them avoid the net. A preliminary study conducted in Brazil found that using plastic bottles on nets was effective at reducing the bycatch of franciscana dolphins, a threatened river dolphin species. It's a realistic option, says Dolman, in places where fishermen don't have the funds to buy and maintain pingers.
Practicalities, along with cost, often prevent implementation of bycatch prevention measures, even the ones that work. Many solutions that get developed and tested never end up being widespread.
"We're very good at providing funding for scientists to conduct trials to reduce bycatch, but very rarely do those trials then continue to the whole of the fleet," says Dolman.
For a solution to work on a large scale, a number of conditions must be met, says marine sustainability scientist Lekelia Jenkins of Arizona State University. Policies and regulations need to be in place, and they need to be enforced. And perhaps just as important, the preventive measures need to be practical for fishermen and not add extra time and money to the job. "The smaller the change, and the more it feels like their traditional fishing practices, the more likely they're going to adopt it," Jenkins says.
The human side of the issue also needs to be acknowledged. "Emotionally, fishermen around the world are beat up and beat down," Jenkins says. "We say, ‘You're the problem. You're catching sea turtles and whales. You are the bad guy.'" Instead, fishermen should be empowered and included in the discussions and development of solutions. "The weight of saving the world's oceans," Jenkins says, "can't fall solely on their shoulders."
This story was produced by Knowable Magazine and reviewed and distributed by Stacker.
Copyright 2026 Stacker Media, LLC
This story was originally published May 4, 2026 at 10:00 AM.