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

Report No. 6945
BBN Systems and Technologies Corporation
along the Alaska Peninsula, Aleutians and Pribilof Islands. Spotted seal
males and females are vocal during the spring mating season (Beier and Wartzok
1979). In the spotted seal, this high rate of vocalization lasts about a
month and the seals are relatively quiet for the remainder of the year (Beier
and Wartzok 1979).
In late spring/early summer, gray whales migrate through Unimak Pass,
across the North Aleutian Shelf, north to Nunivak Island, and from there
directly to St. Lawrence Island, from whence they go to feeding grounds in the
North Bering and Chukchi Seas. Migrating gray whales are vocal in the
southern part of their range (Cummings et al. 1968); however, no attempt has
been made to record the sounds of spring migrants.
Summer - During summer, most walruses are distributed along the ice edge
in the northern Chukchi Sea. Smaller numbers are distributed at various
locations in the Bering Sea. Harbor seals are found in nearshore areas, and
spotted seals are found in nearshore areas of the Northern Bering Sea and in
the Chukchi Sea. The ringed seal and bearded seal are widely distributed in
the Chukchi and Beaufort Seas and the ribbon seal is found in offshore waters
of the Bering Sea. Northern fur seals and Steller sea lion females forage at
sea and return to the breeding islands to suckle young. The males leave their
breeding territories and are foraging at sea by early August. Nothing is
known about summer-time underwater sound production by these species.
In summer, gray whales feed in the northern Bering and Chukchi Seas.
Gray whales vocalize when on their summer feeding grounds (Moore and Ljungblad
1984). Bogoslovskaya (1986) believes that gray whales feed in stable groups
and that individuals within the group keep in acoustic contact with one
another when feeding at distances greater than 800 m.
Most bowheads .,ummer in the Canadian Beaufort Sea. Sounds made by
bowheads on the summer feeding grounds are of the same type as those recorded
during spring migration, with exception that songs have not been recorded in
summer (Wiirsig et al. 1985).
Many white whales summer in the Canadian Beaufort Sea but others occur in
Bristol Bay, Cook Inlet and Norton Sound. In summer, white whales are generally
found in nearshore waters and make daily movements into estuaries. The
white whale is very vocal when in its estuarine habitat (Ford 1977; Sjare and
Smith 1986a,b). Its acoustic behavior during the time when it is not in
estuaries is unknown.
.The killer whale is widely distributed throughout the Bering Sea all year
round and is found in the Chukchi Sea in summer. Killer whales appear to be
vocal at all times (Ford and Fisher 1983; Hoelzel and Osborne 1986).
Humpback whales summer in southeast Alaska, the Gulf of Alaska, Bering
Sea and occasionally in the Chukchi Sea. They are vocal in summer but the
rate of vocalization is lower than when they are on the winter grounds
(Thompson et a1 . 1986 ) .