Sea lions are among the most commonly entangled and bycaught marine mammals globally, suffering severe injuries and death from fishing gear interactions that cause prolonged suffering before rescue or death.
Sea lion entanglement welfare is particularly distressing because animals frequently carry gear for extended periods — months or even years — before death or rescue. Monofilament line around the neck creates a slowly tightening ligature that cuts through blubber and muscle as the animal grows, causing progressive pain and eventually penetrating to vital structures. Animals in this condition continue to swim, forage, and socialise, making their suffering invisible to casual observers but agonising at close inspection. Intentional shooting of sea lions by commercial and recreational fishermen frustrated by competition for fish creates acute welfare harm; documented cases show survival with embedded bullets that cause chronic pain and infection. The solution requires both gear modification to reduce entanglement risk — weak links, pingers, modified net designs — and enhanced enforcement of marine mammal protection laws against deliberate harm.