Sea Otter Mortality at Kodiak Island, Alaska, during Summer 1987

A die-off of sea otters (Enhydra lutris ) occurred in the Kodiak Archipelago, Alaska, during summer 1987. Previous die-offs of sea otters were related to a combination of food stress and inclement weather during winter. The magnitude and timing of the recent die-off at Kodiak Island were unexpected because large numbers of sea otters have occupied the area only since the late 1970s and food available to sea otters is patchy but still abundant. In addition, with exception of a 2-week-long period of storms during June, the weather was moderate throughout the summer. We have not observed incidents of mortality of similar magnitude at Kodiak Island during 3 other years of field work of equal or greater intensity. Of 28 sea otters for which sex was determined, 24 (86%) were males and four (14%) were females. Sea otters often segregate by sex. From the high proportion of males we infer that the source of mortality was highly localized.