Bycatch

Bycatch is the unintended capture of organisms during fishing directed at another species. It includes non-target fish and other animals, some of which are discarded or die after release.

Fishing gear: Equipment used to catch fish and other aquatic organisms. Mesh size, hooks, and gear placement shape which organisms are caught alongside the target.
Bycatch reduction device: A fishing-gear modification designed to let non-target animals escape while retaining target catch. These devices alter trawl nets to reduce capture of selected non-target species.
Dolphin-safe tuna fishing: Tuna fishing practices and standards intended to avoid or limit dolphin mortality. Dolphin entanglement in tuna nets made bycatch a prominent consumer and policy issue.
Fisheries-induced evolution: Heritable evolutionary change in populations caused by selective pressures from fishing. Selective capture can alter the traits of target and non-target populations over generations.
Target species: The species a fishing operation intends to catch. Bycatch is defined relative to the species the operation is trying to capture.
Trawl fishing: Fishing that pulls a net through the water or along the seabed. Trawl nets can capture many species and sizes in a single tow.
Turtle excluder device: A trawl-net grid and escape opening that allow large animals, especially sea turtles, to exit. It reduces turtle deaths in shrimp trawls without requiring fishers to abandon the gear.
Vaquita: A critically endangered porpoise found only in Mexico’s northern Gulf of California. Entanglement in illegal gillnets is the leading threat to its survival.
Population viability analysis: A method for estimating the likelihood that a population will persist under specified conditions. It helps assess whether bycatch mortality threatens a population’s long-term survival.
Incidental take: The unintended capture, injury, or killing of wildlife during a regulated activity. This broader wildlife-management term overlaps with bycatch but applies beyond fishing.

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