Sea otters are keystone species whose predation on sea urchins maintains the health of entire kelp forest ecosystems. Their welfare is affected by pollution, entanglement, disease, and complex interactions with human coastal activities.
Sea otters face welfare threats that span acute trauma and chronic environmental degradation. Oil spill impacts are particularly severe: oiled otters experience hypothermia as fouled fur loses insulating capacity, along with toxicosis from ingesting oil while grooming. Even brief oiling exposure can be fatal. Domoic acid poisoning from harmful algal blooms causes seizures, disorientation, and death in affected animals - a welfare problem likely to worsen as ocean temperatures rise and algal bloom frequency increases. Shark predation causes violent death but is a natural ecological interaction; the welfare concern is whether shark predation rates are elevated by human activities that increase otter vulnerability. Human-caused boat strikes and fishing gear entanglement add to the welfare burden.