NMML Bering Sea Cetacean Survey 2000

Original provider:
National Marine Mammal Laboratory

Dataset credits:
National Marine Mammal Laboratory

Abstract:
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 = 12 m) at survey speeds of 18.5-22 km h-1 (10-12 knots). Transect survey effort was 2,194 km in 2000, in a study area 158,561 km2. An additional 402 km of trackline was surveyed in 2000 while in transit to or from pollock survey way points. Fin whales (<i>Balaenoptera physalus</i>) were the most common large whale, and Dall's porpoises (<i>Phocoenoides dalli</i>) were 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 (<i>Megaptera novaeangliae</i>), 1,003 (CV = 0.26) minke whales, 9,807 (CV = 0.20) Dall's porpoise, and 1,958 (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. Clearly, additional surveys and concomitant assessment of cetacean prey are needed to better define their role in the Bering Sea ecosystem. Such surveys, combined with measures of local hydrography and prey field should be the goal of future cetacean assessments.