Fish discarded alive at sea from commercial fishing operations face high mortality rates from injury, decompression barotrauma, and thermal shock, representing billions of individual deaths annually with significant welfare implications.
Discarded fish experience decompression injuries during ascent from depth that rupture internal organs and displace the swim bladder, causing severe physiological stress and pain. Thermal shock from cold seawater to warm surface temperatures adds additional stress. The majority die within hours of discard despite appearing alive at the surface. The scale of global discards represents enormous preventable suffering that selective gear and fishing practices can substantially reduce.