Ivy Pepin
Amid grim reports on the impacts of overfishing, NOAA Fisheries found that the average American still ate 19.2 pounds of seafood in 2019. But a more terrifying statistic is the number of marine animals killed without ever showing up on people’s plates.
Every day, the fishing industry releases thousands of miles of fishing line and netting into the oceans—hauling in untold numbers of fish and marine life for human consumption. We see the animals they catch show up on seafood restaurant menus, in the form of frozen fish sticks, or laid out on ice at the supermarket. But there’s also a whole world of destruction that we don’t see. It’s called bycatch, and it’s one of the most formidable threats facing our oceans today.
What is bycatch?
“Bycatch” is the term used by the fishing industry to describe any “non-target animals” they inadvertently catch while fishing—whether fish, mammals, sea turtles, or seabirds. Generally, animals caught as bycatch are tossed back overboard, dead or dying. According to NOAA Fisheries, bycatch also includes the animals we never see above water: marine life injured by an encounter with fishing gear and vessels.
Sadly, countless marine animals are caught as bycatch every year—brushed off as “collateral damage” by the fishing industry. This has resulted in widespread species extinction, habitat destruction, and irreversible damage to ocean ecosystems. Today, our oceans are under immense strain, with the United Nations Food and Agriculture Organization (FAO) stating that more than a third of fish stocks are overfished.
Levels of bycatch peaked in the late 1980s, and mitigation efforts have resulted in some progress over the last few decades. But despite those measures, bycatch remains a persistent problem—amounting to 7.3 million tons or more every year. Experts say that, rather than reflecting progress, lower levels of bycatch today may be the result of a decline in the overall number of marine animals in the ocean. In an interview for Reuters, Dirk Zeller of the University of Western Australia notes, “We suspect that (the decline) is because overfishing ... has already depleted the species being discarded.”
Why does bycatch happen?
Much of the bycatch that happens today is due to non-selective fishing gear. Modern fishing gear is highly unselective—meaning that while it’s very efficient at catching target species, it catches lots of other animals, too. According to the World Wildlife Fund, “incidental capture of turtles by longlines, trawls and gillnets is the single greatest threat to the survival of most populations.”
Here are the major kinds of non-selective fishing gear used today:
Shrimp trawling
“Bottom trawling,” one of the most starkly wasteful fishing practices, involves dragging a net across the ocean floor. While this indiscriminate approach is generally intended to catch shrimp or prawns, the massive nets trap many other animals—including sea turtles, who love to forage at the bottom of the ocean for food. Entangled in the nets and trapped at the bottom of a full net of fish, turtles’ shells and bones often break. Many drown from being trapped underwater or are injured as they’re dropped from a great height onto fishing boats—only to die once they’re tossed back into the ocean.
It’s not only turtles who are vulnerable to bottom trawling. The practice also damages coral reefs, critical habitats for scores of marine life. The enormous nets get tangled in corals, plundering the fish who live there and upsetting delicate ecosystems—turning colorful hubs of biodiversity into barren gray landscapes. Beyond the animals caught in these nets, they also damage thriving ecosystems that countless animals rely on for survival—making the true level of their destruction nearly impossible to quantify.
Longlining
Another bycatch-heavy fishing practice is longlining, a commercial fishing method that involves sending out a single line with hundreds or thousands of baited hooks attached at intervals. While the method usually targets tuna, halibut, and swordfish, those aren’t the only animals who go after these “J hooks” (named for their shape). Longlining also catches countless non-target fish, including sharks and juvenile tuna. When juvenile fish are caught, they never reproduce—disrupting the predator-prey balance and damaging ecosystems.
Populations of loggerhead and leatherback turtles, already listed as vulnerable by the IUCN Red List of Threatened Species, are further decimated by longline fishing. These turtles find themselves painfully hooked by their mouths, flippers, or necks as they search for food. Worse, they often swallow the hooks, which become stuck in their digestive tracts—leaving them at risk of starving to death. Sadly, hundreds of thousands of endangered loggerhead turtles and critically endangered leatherback turtles drown on longlines every year.
Longlining also impacts animals above the water. When seabirds dive beneath the surface to do their own fishing, they often get caught in longline hooks and drown as they try to escape. Every year, an estimated 100,000 birds—including threatened and endangered species like the albatross—die as a consequence of longline fishing. While mitigation methods exist (like “night setting,” or setting lines only at night when the albatross isn’t feeding), research reveals that vessels show a “low level of compliance” with regulations intended to reduce albatross deaths.
Gillnets
Another of the most damaging types of fishing gear is the gillnet, an enormous mesh net that catches fish by their gill coverings. Up to 100 feet deep and several miles long, these lethal nets are designed to disappear in the water, nearly impossible for marine life to see. As a result, they capture many more animals than the intended species—including juvenile fish, sharks, seabirds, and turtles. Any animals larger than the mesh holes in the gillnet are vulnerable.
In addition to being hard to see, gillnets are difficult for cetaceans (whales, dolphins, porpoises) to detect by echolocation. According to the World Wildlife Fund, gillnets are the “single largest cause of mortality” for small cetaceans—entangling over 300,000 small whales, dolphins, and porpoises every year. When gillnets are lost, they’re rarely recovered, continuing to capture marine animals for years to come.
What percentage of fishing is bycatch?
Because bycatch happens out at sea, often beyond the reach of regulations, it’s notoriously difficult to measure and presents an enormous challenge for conservation efforts. While the most recent and conservative analyses of bycatch percentages show a rate of about 10%, some estimates have been as high as 40%. That means for every ten fish that are caught at sea, at least one is tossed back to die.
What is done with bycatch?
Animals caught as bycatch are usually thrown back into the ocean. While this might seem like a good thing, the majority of them will not survive—having been killed or critically injured by fishing gear or suffocated while being trapped under or above the water.
Why is bycatch discarded?
Species caught as bycatch are often protected or regulated, meaning they can’t legally be sold (or even, in some cases, caught). Even if the animals aren’t endangered, they may be juvenile, diseased, undersized, or outside the target species. Any animal considered “low-value” by the fishing industry will be thoughtlessly discarded—tossed back into the ocean to die.
As NOAA Fisheries suggests, finding ways to use the animals caught as bycatch can help mitigate its negative impacts. The 2016 National Bycatch Reduction Strategy encourages “increased utilization" of animals who are caught lawfully and discarded, mainly by creating incentives to help fishermen sell more of the fish they accidentally catch. While this can help reduce waste and provide economic benefits to the fishing industry, it’s a retroactive solution—and it doesn’t apply for the many animals who are caught illegally. Reducing the number of animals caught as bycatch in the first place will be critical to protecting the biodiversity of our oceans.
Why is bycatch a problem?
Bycatch worsens issues for protected or endangered species, like whales and sea turtles. But when any marine animals die, endangered or not, they can’t reproduce—derailing efforts to rebuild fish stocks and making it difficult for populations to recover. This can change the availability of prey, upsetting the delicate balance of entire ecosystems. Not only does bycatch devastate populations of marine animals, but it can also decimate marine habitats by damaging corals and sponges—impacting the innumerable species that call these reefs home. A report by Oceana calls bycatch “one of the largest threats to maintaining healthy fish populations and marine ecosystems around the world.”
The negative impacts of bycatch are far-reaching and essentially incalculable—and not just for marine life. Along with damaging ocean ecosystems, bycatch hurts local and indigenous communities who have lived alongside marine ecosystems for thousands of years. Beyond providing a food source, fishing is culturally important for many coastal communities. As huge commercial ships deplete marine life in these areas, many people are losing access to traditional fishing grounds they have stewarded for centuries.
When did bycatch become an issue?
The problem of bycatch first attracted widespread attention in the late 1980s, following the release of undercover footage by biologist Sam LaBudde. His 5-month investigation showed that tuna fishing vessels were intentionally encircling dolphins with huge purse seine fishing nets as a shockingly cruel fishing strategy. Because yellowfin tuna often congregate underneath dolphin pods, the fishers’ brutal method was catching lots of tuna—and killing dolphins in droves. Shortly afterward, thanks to a consumer boycott of tuna, the “dolphin-safe” tuna label began appearing in grocery stores in the 1990s.
However, labels like “dolphin-safe” have long been criticized by researchers and advocates alike—and bycatch was a problem long before the public was made aware of it. One of the greatest challenges in understanding and mitigating bycatch is that it remains largely undocumented—and one nebulous “dolphin-safe” label simply isn’t enough.
Which species are most affected by bycatch?
Cetaceans
Marine mammals (or “cetaceans”), like dolphins and whales, regularly become tangled in nets intended to catch tuna. A 2020 study estimated that commercial fishing killed over 80% of dolphins—at least four million—in the Indian Ocean alone. According to Oceana, bycatch exceeds legal mortality limits for at least 20% of marine mammal populations in the United States.
Albatross
The fishing industry is just as devastating for seabirds, who are often attracted by hooks being baited on the surface of the water. As they swoop in for a piece of bait or dive underwater for food, they are frequently caught on J hooks or ensnared by nets—only to drown beneath the surface. This includes the albatross, one of the most threatened species of seabird. A 2019 study found that not only is industrial fishing a major threat to albatrosses—but fishing vessels routinely ignore regulations put in place to save the birds from extinction.
Sea turtles
NOAA Fisheries names bycatch “one of the most serious threats to the recovery and conservation of sea turtle populations.” North Pacific loggerheads, whose population has declined by 50–90% over the last 50 years, are edged closer to extinction every time they are inadvertently caught on a longline hook or in a shrimp trawling net. Even so, the managers of federal fisheries authorize commercial fisheries to kill tens of thousands of sea turtles every year, largely by shrimp trawls in the Gulf of Mexico.
Sharks
Sharks are among the most vulnerable marine animals when it comes to bycatch. Because sharks and fishing vessels often take the same fishing routes, these animals are particularly susceptible to being accidentally caught on a longline or ensnared in a gillnet. As apex predators, sharks are critically important to the balance of ocean ecosystems—yet, researchers estimate that 100 million are killed from fishing activities every year. To make matters worse, sharks are slow to reproduce, making it even more difficult for them to gradually rebuild their populations. This combination of factors has already endangered some shark species almost beyond recovery.
How to prevent bycatch
While bycatch is an incredibly difficult problem to solve, there are proven solutions that demonstrably reduce the number of animals caught inadvertently.
Alternative gear
There are numerous types of alternative fishing gear, improved practices, and technological solutions to reduce bycatch. For example, NOAA Fisheries has developed turtle excluder devices designed to eject sea turtles caught in trawl nets. World Wildlife Fund has introduced “circle” hooks, which are far less likely to be swallowed by turtles than J-shaped hooks. And an innovative project in Indonesia has proven that electronic devices, or “pingers,” emitting sounds can deter dolphins from swimming too close to fishing nets.
Establishing guidelines
Another important way to mitigate bycatch is to ban or regulate fishing in areas where levels of bycatch are high. When fisheries are unregulated or poorly managed, fishers ignore guidelines like quotas, net sizes, and permitted fishing areas—all important measures designed to reduce bycatch. World Wildlife Fund provides a downloadable set of guidelines for fishers on safely releasing bycatch.
Reducing fish consumption
And of course, one of the most powerful ways to help mitigate the bycatch crisis is to leave fish off your plate. When we refuse to eat marine animals, we reduce demand for seafood—and chip away at the industry’s incentive to destroy ocean ecosystems. Now, with so many delicious plant-based alternatives to seafood, it’s easy to choose foods that are kinder to marine life and the environment.
Conclusion
You might see lobster rolls, shrimp scampi, or baked salmon on a restaurant menu. What you won’t see are the ensnared dolphins, hooked sea turtles, and drowned albatross that died along the way. The real issue isn’t just the fish people are eating—it’s the countless marine animals who are killed or injured in the process.
The fishing industry is decimating delicate ocean ecosystems, and many of the animals they catch don’t even end up as food. Luckily, you can do your part in reducing demand for seafood simply by choosing alternatives. With more plant-based seafood options than ever, you can help prevent bycatch—and the suffering of sea turtles, dolphins, and more marine life—by choosing to leave seafood off your plate.