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

Report No. 6945
BBN Systems and Technologies Corporation
Minke Whale (Balaenoptera acutorostrata). The minke whale is a widely
distributed whale, occurring in many oceans of the world in both the Northern
and Southern hemispheres. In Alaska it is found in the Gulf of Alaska and the
Bering Sea, occupying both shallow shelf and deep offshore waters (Fig. 2.6).
It is common in shallow coastal waters of the Gulf of Alaska from April to
October; there have been a few winter sightings in the Gulf of Alaska (Calkins
1986). In summer its range extends northward into the southern Chukchi Sea,
where there are records from Kotzebue south (Frost et al. 1983). Davis and
Thomson (1984) regarded the minke whale as rare or extremely uncommon in the
Chukchi Sea planning area. In winter the population shifts southward, but the
minke whale is believed to be a year-round resident in the Bering Sea. Minke
whales were recorded during surveys conducted in the Navarin Basin planning
area during all four seasons and were observed near the fringe of the ice
front during winter surveys (Brueggeman 1984). Surveys in the Bering Sea
(including the St. George and North Aleutian Basin planning areas) support the
suggestion that some minke whales inhabit the Bering Sea year round. These
results included winter and spring observations of minke whales near the pack
ice edge (Leatherwood et al. 1983). In summary, minke whales may be expected
to occur at least for a portion of the year in all planning areas south of,
and including the Hope Basin area. The demarcation between the seasonal and
year-round ranges shown on the distribution map is based on few data and is
speculative.
North Pacific minke whales are thought to breed throughout the year, with
calving peaks in December and June. Leatherwood et al. ( 1983) recorded one
calf in May and another in August in the southeast Bering Sea.
Humpback Whale (Megaptera novaeangliae). The humpback whale is a
cosmopolitan species found in all oceans. In general, it concentrates in
coastal areas, but migrates through deep areas and also occurs regularly
around shoals and offshore islands. It occupies Alaskan waters in spring,
summer and fall, and some may occasionally venture as far north as the
southern Chukchi Sea.
Important summering areas include the southeast Bering Sea, the
Aleutians, Shelikof Strait, the Gulf of Alaska and southeast Alaska. Wada
(1981) found highest densities of humpbacks in a region south of the Alaska
Peninsula that corresponds to the Shumagin and Kodiak planning areas, and
along the southeast Alaska coast in the Gulf of Alaska planning area. The
numbers of hmpbacks occupying Alaskan waters are not large. Rice and Wolman
(1982) estimated that the total North Pacific population of humpbacks on the
summer feeding grounds averaged only 1200 individuals. Morris (1981)
estimated that 200 humpback whales were widely distributed during summer in
the Bering Sea. In this area they are most numerous in the waters between the
Pr ibilof Islands, Nunivak Island and Cape Newenham. Leatherwood et a1 . ( 1983)
recorded only two individuals on surveys in this particular part of the Bering
Sea and Brueggeman et al. (1984) did not record any humpback whales during
their surveys in the Navarin Basin. Brueggeman et al. (1987) recorded
humpback whales in the Shumagin, but not the North Aleutian and St. George
planning areas. Brueggeman et al. (1988) conducted shipboard surveys during