Little is known about the occurrence of cetaceans found in offshore waters in the Gulf of Alaska (GoA); however, whaling records and a few recent surveys have shown this area to be important habitat. The United States Navy maintains a maritime training area in the central GoA east of Kodiak Island, and has requested additional information on marine mammal presence and use of this area. To determine the occurrence and distribution of marine mammals in and around the Navy training area, a line-transect visual and acoustic survey was conducted 10-20 April 2009 from the NOAA Ship Oscar Dyson. The primary survey area encompassed nearshore, shelf and offshore pelagic waters of the central GoA. Survey lines were designed to provide equal coverage of the nearshore and offshore habitat.
During this project, the visual survey covered a total of 432 nautical miles (800 km) oneffort, while transit- and fog-effort legs accounted for 312 nautical miles (578 km). There were a total of 96 sightings (453 individuals) of 11 confirmed marine mammal species. These included fin, humpback, gray, and minke whales, as well as killer whales, Dall’s and harbor porpoise, Pacific white-sided dolphins and Steller sea lions, harbor seals and sea otters. Additionally, there were 36 sightings (46 individuals) of unidentified large whales, dolphins, and pinnipeds. Acoustically, operations were conducted 24 hours/day surveying a total of 1900 nautical miles (3519 km) and recording 49 acoustic detections of sperm whales and killer whales. At least nineteen killer whales and four fin whales were photographed for photo-identification purposes. Despite a number of logistical and time limitations, the survey achieved its primary objectives and provided new information on marine mammal occurrence and abundance in the region. Sightings should be adequate to allow density and abundance estimates of several species. Photographic identification of killer whales will provide important data on the identity of these whales, since several eco-types of killer whales have been documented in Alaskan waters. Overall the cruise provided valuable new data and, with additional analyses of the visual and acoustic data, promises to achieve the objectives of the cruise.
Rone, B., A. Douglas, P. Clapham, A. Martinez, L. Morse and J. Calambokidis. 2009. Cruise Report for the April 2009 gulf of Alaska Line-Transect Survey (GOALS) in the Navy Training Excise Area. Report issued by National Marine Mammal Laboratory and Cascadia Research. Naval Postgraduate School Tech Report # NPS-OC-09-007. (See Rone et al. 2010 for final publication of this work).Download PDF
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