Deep sea fish including Patagonian toothfish are caught in fisheries that cause significant individual welfare harm through barotrauma and capture stress.
Deep sea fish experience severe welfare harm from the physics of rapid depth change. Barotrauma causes gas expansion in the swim bladder that forces stomach and other organs out through the mouth, causes the eyes to protrude, and results in extreme internal pressure. Fish surviving the ascent experience this before death by asphyxiation or mechanical killing. The welfare harm of deep sea fishing is related to the depth fished and the speed of ascent, not to species or fishery management quality.