All seven sea turtle species are threatened or endangered, and longline fishing bycatch is a leading cause of mortality. Circle hooks, fish bait, and line setters have dramatically reduced bycatch in some fisheries.
Sea turtles hooked on longlines may remain on the line for hours to days before the line is hauled. Entanglement and hook ingestion cause injuries including broken flippers, internal hook damage, and drowning. Turtles that are released may survive if hooks are removed carefully, or die from internal injuries if hooks are cut rather than removed. The scale of global longline deployment makes sea turtle bycatch one of the largest ongoing marine vertebrate welfare problems.