Sea otters are a keystone species whose welfare is tightly linked to kelp forest ecosystem health. Oil spills, shark predation, and pollution pose ongoing welfare threats.
Sea otter welfare involves both individual health and the ecosystem integrity they depend on and maintain. Oil spills are the most acute welfare emergency — oiled otters lose the dense fur insulation that replaces the blubber other marine mammals use for thermal regulation, causing rapid hypothermia. Rehabilitation of oiled otters is intensive and requires specialized facilities; survival rates have improved significantly through experience with major spill events. Shark predation — primarily by great white sharks — is an increasing cause of mortality and injury to the recovering southern sea otter population, with attacks rarely fatal but causing significant injury. Domoic acid poisoning from harmful algal blooms kills significant numbers of otters, with toxin accumulating through the shellfish they eat. The ecosystem services sea otters provide — maintaining urchin populations that would otherwise destroy kelp forests — make their welfare a matter of much broader ecological and economic importance.