Blue marlin, sailfish, and other large pelagics are targeted by recreational and commercial fishing, with increasing scientific interest in their cognitive complexity and welfare.
Large billfish welfare raises questions at the intersection of conservation and sentience: fish of this size, speed, and apparent cognitive complexity are poorly served by welfare frameworks designed for smaller species. The stress of multi-hour fights on recreational tackle causes profound physiological exhaustion, scale and mucus loss, and in some cases death after release despite apparent recovery. Commercial longline capture causes slow drowning. Whether their apparent hunting intelligence indicates morally relevant experience remains scientifically unresolved.