Marlins are apex pelagic predators and iconic sport fish. Their welfare in recreational fishing, commercial bycatch, and longline capture deserves serious attention.
Sport fishing for marlin involves prolonged battles lasting from minutes to hours, during which fish experience extreme exertion, lactic acid buildup, and cardiovascular stress. Even fish that are released may die hours later from exertion. Catch-and-release marlin fishing has better outcomes than retention but is not welfare-neutral. In commercial longline fisheries, marlins may be on hooks for 12-24 hours before retrieval. Barotrauma from deep-water capture and rapid retrieval causes internal injuries. Their large size and power make humane handling extremely difficult.