What Is Bycatch In Fishing?

By Oishimaya Sen Nag on April 25 2017 in Environment

This Albatross frantically tries to free itself from a fishing line.
This Albatross frantically tries to free itself from a fishing line.

What is Bycatch?

Bycatch refers to the incidental or unintended capturing and/or killing of non-targeted aquatic species while fishing for another target species. As per the 1997 definition of bycatch provided by the Organization for Economic Cooperation and Development (OECD), bycatch is defined as "total fishing mortality, excluding that accounted directly by the retained catch of target species”. Currently, bycatch is one of the most devastating effects of commercial fisheries on the natural world, killing and maiming large numbers of aquatic fauna, and even pushing many of them to the brink of extinction.

Why Does Bycatch Occur?

Careless, unregulated, and unscientific fishing practices are the primary causes of bycatch. The non-target species, being attracted to the bait set out by fishermen for target species or to the target species itself, find themselves trapped, entangled, or hooked to the fishing gear, and those that do manage to escape often do so with serious injuries, and still often ultimately die. The highest rates of bycatch are associated with the practice of tropical shrimp trawling, which produces more than one-third of the world’s bycatch alone. In fact, for every one kilogram of shrimp secured through such trawling, there is 5.7 kilograms of consequent bycatch. Cetacean and fin-fish species alike are unintentionally caught by such shrimp trawls, and by the time the bycatch is discarded into the ocean, most of the species are either dead or well on their way to dying. There are also reports that recreational fishing practices also generate a significant volume of bycatch, most of which goes undocumented in official statistics.

Species Most Affected By Bycatch

Marine mammals such as cetaceans, birds such as albatrosses, and marine reptiles such as sea turtles face the worst threats from bycatch. As per the World Wide Fund for Wildlife's estimates, 6 cetacean species could become extinct within a decade, with the primary reason being death by entanglement in fishing nets. Dolphins often find themselves caught and killed in tuna nets. Only a few hundred members each of Maui's dolphins, Irrawady dolphins, and Vaquita, respectively, remain in the world’s oceans today, as most have been lost to the outcomes from exploitative fisheries. Often, these cetaceans, though caught as bycatch, are not discarded, but instead retained by fishermen for their own commercial values. This further leads to the loss of these animals, as it is in fact viewed as lucrative to have such bycatch. Besides marine aquatic species, sea birds like albatrosses also become caught up in the deadly fishing nets when, attracted to the offal and other bait set out during fishing, these unsuspecting birds get hooked to the fishing gear and drown as a result. Around 100,000 albatrosses are killed each year in this manner, many belonging to species categorized as "threatened" by the International Union for the Conservation of Nature's Red List. Sea turtles, including Loggerheads, Leather-back sea turtles, and Kemp’s Ridley turtles, are also caught and killed in large numbers in shrimp trawl and other nets.


Today, there is an urgent requirement seen for implementing new rules and regulations to control the fishing practices of the world’s commercial, recreational, and sports fisheries alike. One of the ways to reduce bycatch would be to permanently or temporarily ban fishing in certain areas of the oceans where the probability of trapping large volumes of bycatch is high. The other way to reduce bycatch could involve modifications to the commonly used fishing gear. "Bycatch Reduction Devices" (BRDs) and "Nordmore grates" are modifications to the designs of fishing nets that allow many species of fish to escape being trapped during shrimp trawling practices. BRDs have already reduced finfish bycatch by 30% when and where implemented. Another innovative piece of fishing gear, the "turtle excluder devices" (TEDs) have been developed by the National Marine Fisheries Service, and have reduced turtle bycatch quite significantly. Several measures are also recommended to save birds from dying during fishing activities. The setting of fishing lines at night, the use of streamers to scare off birds from baited hooks, using weights to sink the nets quickly, and avoiding the discharge of offal while deploying fishing lines could all help reduce bird deaths as a result of bycatch. Some of these means and newly implemented policies are already exhibiting some degree of success.

In the CCAMLR zone in the Southern Ocean in South Georgia, a 99% reduction in seabird deaths as a result of bycatch has been observed. Regulations on seabird catches in South Africa and Brazil has also yielded a high degree of success in reducing their incidence. However, despite the existing rules and regulations, corrupt governments, illegal fisheries, non-complying fishing companies, and the insatiably high demand for sea-food species are factors making it extremely difficult to check bycatch on a massive scale. Thus, to save the world's oceans from becoming fishless, a greater public awareness regarding the adverse effects of bycatch and stricter implementation of bycatch reduction policies are in dire need.

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