Deep-sea fishing affects animals in the least understood ecosystems on Earth, with welfare implications for species including gulper eels and other deep-sea fish that may face slow recovery from population disturbance.
Deep-sea fishing welfare is poorly understood because the animals live in environments difficult to study. Fish brought from deep water in trawl nets experience rapid decompression that causes gas bladder expansion, internal injury, and death — a prolonged and painful process. The ecological destruction of deep-sea sponge and coral communities by bottom trawling eliminates habitat for fish and invertebrates whose welfare and sentience we have barely begun to assess. The precautionary principle applies strongly to deep-sea ecosystems where the consequences of fishing are irreversible on human timescales.