Deep-Sea Fishing Barotrauma in Bycatch

Fish caught from depth undergo barotrauma as they are rapidly brought to the surface, causing gas expansion injuries that are painful and often fatal even when fish are released.

Key Facts

Barotrauma occurs when gases in a fish's swim bladder expand rapidly during ascent from depth
Fish with barotrauma often cannot swim back down after release, floating helplessly at the surface
Common external signs include bulging eyes (exophthalmia), everted stomachs, and distended abdomens
Even fish that appear to swim away after release commonly die from barotrauma within hours
Descender devices can return fish to depth where pressure equalizes and recovery is possible
Rockfish and snapper are among the most commonly affected species in recreational and commercial fishing

Welfare Considerations

Barotrauma represents a welfare concern for potentially billions of fish caught as bycatch or in catch-and-release recreational fishing annually. The rapid pressure change from deep water to surface causes gas in the swim bladder to expand explosively, rupturing tissue and pushing organs out of body cavities. Fish experiencing severe barotrauma are unable to swim, making predation certain even if not handled further. The phenomenon is particularly relevant in deep-water fisheries where bycatch of non-target species is common. Descender devices effectively address the problem but require behavioral change from fishers.

What You Can Do

Use descender devices when fishing at depth to return bycatch to depth for recovery
Support regulations requiring descender device use in deep-water recreational fisheries
Advocate for bycatch reduction measures in commercial deep-water fisheries
Learn to identify barotrauma signs and respond appropriately when releasing fish
Support research into fish pain and welfare to strengthen evidence base for policy