NMML 2002-2010 Bering Sea Shelf Cetacean Survey

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) in association with a NOAA/Alaska Fisheries Science Center’s pollock stock assessment survey aboard the NOAA ship Miller Freeman (2002 and 2004) and the NOAA ship Oscar Dyson (2008 and 2010). In 2002 and 2004, the surveys were a continuation of those done in 1999 and 2000, taking advantage of the survey platform as it ran transects through SEBS. In 2008 and 2010, the cetacean survey was included as part of the Bering Sea Integrated Ecosystem Research Program, a NPRB funded project to test and improve our understanding of effects of climate change and management actions on the Bering Sea ecosystem. Methods in all years were the same with three observers rotating through two 25x (Big Eye) binocular positions and one recorder on the flying bridge. Survey effort was conducted along the pollock survey transect lines, weather permitting. Additional effort was conducted while in transit to and from pollock survey waypoints. Transect survey effort was 3,761 km in 2002, 1,692 km in 2004 (observers were present for only half of the survey), 3,255 km in 2008 and 1,681 km in 2010. The following cetacean species were recorded: fin whale (Balaenoptera physalus), sei whale (Balaenoptera borealis), minke whale (Balaenoptera acutorostrata), humpback whale (Megaptera novaeangliae), gray whale (Eschrichtius robustus), sperm whale (Physeter macrocephalus), Baird’s beaked whale (Berardius bairdii), Stejneger’s beaked whale (Mesoplodon stejnegeri), killer whale (Orcinus orca), Pacific white-sided dolphin (Lagenorhynchus obliquidens), Dall’s porpoise (Phocoenoides dalli), and harbor porpoise (Phocoena phocoena). Pinniped species were also recorded to include the Steller sea lion (Eumetopias jubatus) and the northern fur seal (Callorhinus ursinus), as well as the sea otter (Enhydra lutris). Fin whales were the most common large whale, and Dall's porpoises were the most common small cetacean. Distribution, abundance estimates and population trends for fin, humpback, and minke whales, and Dall’s and harbor porpoise are currently being analyzed. Purpose: The primary purpose of this survey was to estimate the abundance of and to describe the distribution of whales and porpoises in the eastern Bering Sea in relation to the oceanographic domain.