bycatch

In commercial fishing, that part of the catch that is unwanted. Bycatch constitutes approximately 25% of global catch, and consists of a variety of marine life, including fish too small to sell or otherwise without commercial value, seals, dolphins, sharks, turtles, and even seabirds.

Bycatch can sometimes exceed target catch; for example, trawling for shrimp can result in discarded animals outnumbering shrimp by 125–830%. An estimated 55,000 sea turtles die in shrimp trawls annually in US waters. It is not only large nets that cause bycatch: more than 40,000 albatrosses drown each year in the southern hemisphere as a result of becoming hooked by fishing lines when they eat the squid bait set for bluefin tuna.