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

Report No. 6945
BBN Systems and Technologies Corporation
although no sightings were recorded during the fall period, it should be noted
that no surveys were conducted in September. October and November surveys
resulted in no fin whale sightings, but it is probable that some fin whales
are present in September. Leatherwood et al. (1983) recorded the fin whale in
Shelikof Strait in early September. ,
Brueggeman et al. (1988) conducted shipboard surveys in the Shumagin,
Kodiak, and lower Cook Inlet planning areas during June-July 1987. They
recorded densities of fin whales in the Shumagin Planning Area about five
times higher than those recorded by Brueggeman et al. (1987). Brueggeman et
al. (1988) calculated minimum abundance estimates of 943 (+536 SE) fin whales
for the Shumagin Planning Area. They concluded, based on the results of the
1985 and 1987 surveys, that "approximately 1000 finbacks or fewer summer in
the Shumagin Planning Area.
Port Moller/Nelson Lagoon
Marine mammal populations near Port Moller were surveyed recently by Troy
and Johnson ( 1987). These aerial and ship-board surveys covered the North
Aleutian Shelf region from Unimak Pass to Cape Seniavin (about 45 km east of
Port Moller) to depths of about 60 m. Common marine mammals in the area
studied are Steller sea lion, harbor seal, sea otter, Dall's porpoise, harbor
porpoise and gray whale (Table 2.3).
The sea otter is by far the most common marine mammal in this area.
Otters are present year-round. They are relatively common to about the 50 m
isobath and are generally most common in the 30-40 m,depth range.
Gray whales migrate through the area in spring and fall and small numbers
summer in the area. They are found in coastal waters, in the shallowest
waters surveyed by aerial and ship-board observers.
Steller sea lions are found in the area year-round. Sea lions were found
primarily in the shallowest waters surveyed, and most were seen well west of
the Port Moller area, near Unimak Island.
Harbor seals were also found in shallow coastal waters. They are most
common in the summer months. The winter decline may indicate a seasonal
exodus from the study area, or reduced sightability during seasons when they
do not haul out. The Port Moller/Nelson Lagoon area is a major haul out site
and as many as 8000 harbor seals have been recorded there (Frost et al. 1982).
Peak use of haul-out areas occurs during the molt in June and July and tapers
off in September and October, after which harbor seals spend more time in the
water.
The two species of porpoise occurred only seasonally in the study area,
and in waters of variable depth. During a July 1985 cruise Dall's porpoise
were found in fairly shallow (30-40 m) waters even though they are considered
a deep-water species. Sightings of this species in May 1985 were in waters
>60 m deep. Harbor porpoise recorded during shipboard surveys occurred in
waters less than 30 m deep (July 1985) and in waters 40 to 50 m deep (May
1985).