Sea otters (Enhydra lutris) are keystone species of kelp forest ecosystems and among the most welfare-visible marine mammals due to their relatable behaviour and vulnerability to human-caused pollution. Oil spills and environmental toxins cause acute and chronic suffering to individual otters and undermine population recovery.
Oil contamination causes severe acute suffering: otters coated in oil lose insulation, develop hypothermia, and frantically attempt to groom contaminated fur — inadvertently ingesting toxic hydrocarbons that cause organ damage. Rescue and rehabilitation is labour-intensive (round-the-clock care for weeks) but effective when conducted rapidly. Chronic toxin exposure from algal blooms causes seizures, disorientation, and death in affected animals. Toxoplasmosis causes fatal encephalitis — a disturbing neurological deterioration. The California sea otter population is particularly vulnerable because it is geographically isolated, small, and dependent on nearshore habitat highly vulnerable to land-based pollution. The connection between domestic cat ownership (and cat faeces entering waterways) and sea otter mortality is a striking example of how companion animal management affects wild animal welfare.