ABSTRACT
Sea otters differ significantly from other marine mammals in their anatomy, physiology, taxonomy, and behavior; thus, a summary of these features pertinent to their medicine is given below. There are three subspecies, the southern (Enhydra lutris nereis), northern (E. I. kenyoni), and Western Pacific (E. I. lutris) sea otter. The life history traits of sea otters, including their high trophic level, strong site fidelity, and dependence on nonmigratory prey species, make them suitable sentinels for nearshore ecosystem ocean health. Mortality and pathogen exposure in wild sea otters have been investigated by a variety of authors and differ among subspecies (Ames et al. 1983; Kreuder et al. 2003; Goldstein et al. 2011; White et al. 2013; Shapiro et al. 2014; Bartlett et al. 2016). Certain populations may have increased exposure to infectious diseases, possibly linked to anthropogenic stressors, including habitat degradation, municipal runoff, contamination of nearshore waters with terrestrial pathogens, overharvest of marine resources, and climate change (Goldstein et al. 2011). The most common causes of death in southern sea otters include protozoal encephalitis, acanthocephalan-related disease, shark attack, and cardiac disease (Kreuder et al. 2003). Beta-hemolytic streptococci are newly recognized important pathogens in northern sea otters, especially those from Kachemak Bay, Alaska (Counihan et al. 2015).
