NOAA 2006-R103
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NOAA Fisheries Service biologists have completed analysis of data from an aerial survey of beluga whales in Cook Inlet near Anchorage, Alaska. The latest abundance estimate is 278 individual belugas whales in Cook Inlet.

“Although this point estimate is lower than those estimates derived from similar surveys conducted between 1999 and 2004, this estimate is not statistically different from the point estimate of 366 in 2004,” explained Alaska Fisheries Science Center Administrator Doug DeMaster. “The re-calculated trend including this number is also not statistically different from a zero or flat trend. We don’t know whether this lower point estimate for 2005 represents a change in population abundance.”

“We expect a certain amount of variability from year to year and survey to survey, however this estimate falls near the lower limit of the expected variability for a stable population,” said Dr. Rod Hobbs, the Alaska Fisheries Science Center researcher who conducts the analysis to estimate population abundance. “Upcoming surveys should help us understand whether this latest estimate represents a true decline in the population or is a low estimate from a stable population.”

Subsistence harvest of Cook Inlet belugas whales is minimal, contaminant loads are comparable or less than other Alaska and Canada beluga stocks, and the number of stranding events was within the expected range in 2004 and 2005, DeMaster added.

Abundance estimates are calculated from a careful examination of video taken during the aerial passes over groups of belugas. The 2005 abundance estimate of 278 belugas was derived from the average of six flights around Upper Cook Inlet. The population estimate holds a 95 percent confidence interval that the true population of whales lies between 194 and 398 belugas.

NOAA Fisheries Service researchers fly systematic annual surveys in early June in order to take advantage of typically good weather at a time when belugas concentrate near river mouths during fish migrations. In 2005, the surveys were flown daily from May 31 to June 9. The survey effort is concentrated in the upper inlet, north of the East and West Forelands, where belugas are found consistently. The lower inlet is surveyed only once each year, and very few if any belugas are found there. In June, belugas are typically seen in a few dense groups in shallow waters near river mouths, especially the Susitna and Little Susitna Rivers, in Knik Arm and Chickaloon Bay.

The Cook Inlet beluga stock declined by nearly 50 percent between 1994 and 1999, and, in 2000, was declared depleted under the Marine Mammal Protection Act by NOAA Fisheries Service. Beluga hunting restrictions were enacted in 1999. NOAA Fisheries Service has worked with the Cook Inlet Marine Mammal Council, the Native Village of Tyonek, Cook Inlet Treaty Tribes and others over the last decade to prevent excessive harvests and establish agreements for the cooperative management of the whales. In the last seven years (1999-2005), five whales have been taken for subsistence in Cook Inlet.

Last year, NOAA Fisheries Service initiated a routine review of the status of Cook Inlet belugas to consider whether the Cook Inlet stock of beluga whales should be listed under the Endangered Species Act. The agency last reviewed the Cook Inlet beluga stock for listing in 2000. Officials determined at that time that the Cook Inlet stock did not need to be listed under the Endangered Species Act, but the stock is designated as depleted under the Marine Mammal Protection Act.

The Cook Inlet beluga population is one of five beluga stocks (Cook Inlet, Bristol Bay, eastern Bering Sea, eastern Chukchi Sea, and Beaufort Sea) recognized within U.S. waters. Researchers estimate a population of roughly 60,000 belugas in Alaska waters outside Cook Inlet.

NOAA Fisheries Service is dedicated to protecting and preserving our nation’s living marine resources through scientific research, management, enforcement, and the conservation of marine mammals and other protected marine species and their habitat. To learn more about NOAA Fisheries Service in Alaska, please visit our Web site at

NOAA, an agency of the U.S. Department of Commerce, is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners and nearly 60 countries to develop a global monitoring network that is as integrated as the planet it observes.

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Beluga Whales in Alaska and Cook Inlet: