Longline fishing involves stringing out baited hooks on enormous lengths of line to catch large fish and other marine creatures. Particularly when unregulated or poorly practiced, it can have a significant environmental impact by removing big oceanic predators and catching nontargeted fish and other animals.
The most obvious ecological effect of longline fishing is that individuals of the targeted species are caught and processed. Commonly harvested fish in longline industries include tuna and such billfishes as marlin and swordfish. These species are top-level predators that play key roles in the marine ecosystem, so their fisheries must be carefully regulated to prevent overfishing.
Commercial fishing ships use longline fishing to catch sharks for the lucrative shark-fin trade in Asia. This process frequently involves workers removing the shark's fins and discarding the rest of the shark back into the ocean. Because sharks sit atop the oceanic food chain, lower populations can have major ecological impacts. Many countries ban this practice.
A signficant environmental impact of longline fishing is bycatch -- the incidental killing of nontargeted species. Bycatch often includes animals that may go after the longline baits, such as sea turtles, albatrosses and other pelagic birds and predatory fishes. Various mitigation techniques are possible, such as setting longlines in deeper waters or using a different style of hook.
Article Written By Ethan Schowalter-Hay
Ethan Schowalter-Hay is a writer and naturalist living in Oregon. He has written for the "Observer," the Bureau of Land Management and various online publishers. He holds a Bachelor of Science in wildlife ecology and a graduate certificate in geographic information systems from the University of Wisconsin.