As the name suggests, longline fisheries trail a long line, or main line, behind a boat.
Baited hooks are attached to the nets at intervals to attract the target species. Longlines can be set for pelagic (midwater) or demersal (bottom) fishing, depending on the target species.
Without careful management, longline fisheries can have unintended interactions with non-target fish, seabirds, and other marine life. Because of this, to become MSC certified, they are often required to make improvements to their monitoring programs, and to mitigate interactions with non-target species.
Careful data collection and regulations, such as those followed by longline vessels in the Icelandic cod fishery, ensure sustainable catches.