Analysis and Ranking of the Acoustic Disturbance Potential of ...

Report No. 6945
BBN Systems and ~echnologies Corporation
The distribution map distinguishes between areas that bearded seals
occupy seasonally (during the maximum extent of the winter ice) and year
round. The demarcation between these two ranges is arbitrary and doubtless
changes from year to year depending on ice conditions. Some of the areas
shown as seasonally occupied may in fact be occupied year round, especially by
juveniles and subadults. Also, it should be noted that much of the Beaufort
and Chukchi Sea region shown to be inhabited year round is only marginal
habitat in winter because of the great depth of the water and the heavy ice
cover. This region is probably occupied by very low densities of bearded
seals in winter. In some areas bearded seals reportedly maintain their own
breathing holes in the ice in much the same manner as ringed seals (Stirling
and Smith 1975).
Northern Elephant Seal (Mirounga angustirostris). The breeding range of
northern elephant seals extends from islands off Baja California to the
Farallon Islands off San Francisco, California. Non-breeding individuals
occasionally stray into the Gulf of Alaska. None of the Alaska O.C.S. planning
areas represent areas of importance to elephant seals. The northern
elephant seal population is rapidly increasing and Leatherwood et a1 . ( 1983)
speculated that the number of sightings in Alaskan waters may increase in the
future.
Other Marine Mammals
Sea Otter (Enhydra lutris). In Alaskan waters the sea otter occurs in
nearshore waters from the Prince William Sound region in the Gulf of Alaska,
southwestward along the Alaska Peninsula and through the Aleutian Islands.
They also occupy the north coast of the Alaska Peninsula (southwest Bristol
Bay) and small numbers are found in waters near the Pribilof Islands
(Schneider 1976). They have been reintroduced into their former habitat along
portions of Alaska's southeast coast and these populations are expanding
(Calkins 1986) (Fig. 2.22).
In the southeast Bering Sea study area surveyed by Leatherwood et al.
(1983), the sea otter was the third most frequently sighted marine mammal.
Sightings in winter were primarily nearshore. In spring, summer, and fall,
sightings were more widely scattered, with sightings north of the Aleutians,
near the Pribilof Islands, and between the Pribilofs and St. Matthew Island.
They found that most sea otters were in very shallow water (