NMML 1999 Bering Sea Shelf Cetacean Survey

Visual line-transect surveys for cetaceans were conducted in the central-eastern Bering Sea (CEBS) from 5 July to 5 August 1999, in association with a pollock stock assessment survey aboard the NOAA ship Miller Freeman. Observers scanned for cetaceans with 25x (Big Eye) binoculars form the flying bridge (platform height = 12m) at survey speeds of 18.5-22 km h-1 (10-12 knots). Transect survey effort was 1761 km, in a study area 196,885 km2. An additional 609 km of trackline was surveyed, respectively, while in transit to or from Pollock survey way points. Fin Whales (Balaeoptera physalus) were the most common large whale, and Dall's porpoise (Phocoenoides dalli) the most common small cetacean. In the CEBS (1999), uncorrected cetacean abundance estimates were: 3368 (CV = 0.29) fin whales, 810 (CV . 0.36) minke whales (B. acutorostrata), 14,312 (CV = 0.26) Dall's porpoise and 693 (CV = 0.53) harbor porpoise (Phocoena phocoena). 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.