NMML 2000 Bering Sea Shelf Cetacean Survey

Visual line-transect surveys for cetaceans were conducted in the
southeastern Bering Sea (SEBS) from 10 June to 3 July 2000, in association with
a Pollock stock assessment survey aboard the NOAA ship Miller Freeman.
Observers scanned for cetaceans with 25x (Big Eye) binoculars from the
flying bridge (platform height = 12m) at survey speeds of 18.5-22 km h-1 (10-12
knots). Transect survey effort was 2194 km in 2000, in a study area 158,561
km2. An additional 402 km of trackline was surveyed in 2000, respectively,
while in transit to or from pollock survey way points. Fin whales (Balaenoptera
physalus) were the most common large whale, and Dall's porpoise (Phocoenoides
dalli) the most common small cetacean. In the SEBS (2000), uncorrected
abundance estimates were: 683 (CV _ 0.32) fin whales, 102 (CV _ 0.50) humpback
whales (Megaptera novaeangliae), 1003 (CV _ 0.26) minke whales, 9807 (CV _
0.20) Dall's porpoise and 1958 (CV _ 0.21) harbor porpoise. Non-pollock
echosigns observed near cetaceans, some of which may have been cetacean prey,
were not routinely identified during trawl sampling because the research focus
was on pollock abundance assessment. � 2002 Elsevier Science Ltd. All rights
reserved. Clearly, additional surveys and concomitant assessment of cetacean
prey are needed to define their role in the Bering Sea ecosystem better. Such
surveys, combined with measures of local hydrography and prey field should be
the goal of future cetacean assessments.