Movements and Management of Sea Otters in Alaska

Garshelis, David; Garshelis, Judith

From 1979 to 1982 we radiotracked 104 sea otters (Enhydra lutris) and conducted periodic aerial and surface counts of otters to investigate their daily and seasonal movement patterns in Prince William Sound, Alaska. Preferred places for resting and feeding were apparent. Several otters shared the same set of resting and feeding sites, so their daily home ranges greatly overlapped. One study area contained predominantly males (97%), so discrete clusters of nearly coincident daily home ranges within this region were referred to as male areas. A second study area contained several distinct congregations of females; female areas were occupied seasonally by territorial males. Seasonal movements among male or female areas were largely influenced by breeding, pup-rearing, boat traffic patterns, and availability of sites used to escape stormy weather. Movements among female areas were more regular than among male areas, but male areas were further apart so male home ranges tended to be larger. Males often traveled between areas in groups. Breeding males traveled between male areas and female areas, so lifetime home ranges of males probably included much of the geographic range of the population in the Sound. Expansion of this range coincided with drastic reductions in crab numbers, forcing closure of a commercial crab fishery. Management schemes likely cannot alleviate current sea otter-fishery conflicts, but should focus on preventing the development of further conflicts.

Movements and Management of Sea Otters in Alaska

Series

Collections