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

Report No. 6945
BBN Systems and Technologies Corporation
Table 2.5. Densities (no./km2) of Marine Manrmals Estimated From Aerial
Surveys in the Alaskan Beaufort Sea, Especially With Respect to
the "Corona" Site.
Spring
Mar-May
Summer.
June- Aug
- Fall
Sep t -Nov
Winter
Dec-Feb
Bowhead whale 0 0-0.008 0.006-0.0034~ 0
Ringed seal 0.04~-0.41 0.04-0.415 few 0.04-0.41
' Densi ties shown indicate the maximum annual densities observed during August
survey periods in 1985 and 1986 in the continental shelf stratum (Richardson
et al. 1987). Densities are corrected for submerged whales, and whales at
the surface that were not seen by the observers. The study area was centered
about 100 km east of Corona; densities at Corona probably average somewhat
lower.
'Densities shown indicate the maximum annual densities observed during
September and October survey periods in 1985 and 1986 in the continental
shelf stratum (Richardson et al. 1987). Densities are corrected for
submerged whales, and whales at the surface that were not seen by the
observers. The study area was centered about 100 km east of Corona.
3~inged seal densities in areas of pack ice in the Alaskan Beaufort Sea ange
from 0.04 (Burns and Eley 1978) to 0.1 1 (Burns and Kelley 1982) (no./km ,
uncorrected for seals not hauled out or otherwise missed by observers)
observed on aerial 'surveys. The 0.04 figure is a general figure for the
Alaskan Beaufort, while the 0.11 figure was obtained on a brief (140 km)
survey over pack ice between Flaxman Island and Barter Island on 29 May
1982.
'(gverage of six years data from 1970-1982 for fast ice (Burns and Kelley
1982). The study area extended from Flaxman Island to Barter Island.
Surveys were conducted in late May and early June. Ringed seal densities
near Corona might be expected to be comparable to densities shown for pack
ice areas since landfast ice probably rarely extends as far offshore as the
Corona site. However, the densities might be expected to be at the high end
of the pack ice range discussed above, since the area would be fairly close
to landfast ice and the pack ice might be heavy and consolidated, and
therefore more desirable habitat.
'~lthou~h peak numbers of ringed seals would still occur in the Corona area in
June, they probably begin to decline as the ringed seals move offshore with
the retreating pack ice. Most of the population is thought to remain in the
pack ice until freeze-up in the fall (Davis and Thomson 1984).
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