Antibodies to T. gondii have been found in a variety of marine mammals including sea otters, dolphins, seals, and walruses (Table 15.1). Prevalence of T. gondii in sea otters was high but varied between 47 and 100% depending on the category (live versus dead), source (California versus Washington), and the serological test used. Prevalence in sea otters from California was higher than in Washington otters.