A Cook Inlet beluga whale population crash?

A Cook Inlet beluga whale population crash?

 

Cook Inlet’s endangered beluga whale population has fallen to its lowest level in nearly 20 years, with just 284 of the enigmatic white whales counted last summer.

But federal biologists caution the beluga numbers may not have fallen as steeply as the 20 percent decline from 2010 suggests. The number of beluga deaths reported in 2011 was particularly low, raising questions about the population survey conducted in June. Other factors also changed compared to the 2010 survey, including survey conditions and the distribution of the belugas.

The estimates by the National Oceanic and Atmospheric Administration are a key factor in determining the health of the popular whale, a roadside tourist attraction as it surfaces and vanishes while feeding on fish near Anchorage each summer and fall.

Cook Inlet belugas, one of five U.S. stocks, were listed as endangered in 2008 under the Endangered Species Act. Three decades ago, its population was estimated at 1,300 mammals, though scientists’ counting methods were much different back then. Subsistence hunting by Alaska Natives has been blamed for the beluga’s decline, but the animals appear not to have recovered since a legislative moratorium banned hunting in 1999.

The state has little confidence in the yearly estimates, and is challenging the endangered listing in federal court. The state lost its argument in November, but a state official reached Monday said lawyers are reviewing the judge’s decision and considering their next step.

The 2010 estimate found 340 whales.

“Only three dead belugas were reported this year, which indicates that large numbers of mortalities did not occur in 2011,” said Doug DeMaster, director of the Alaska Fisheries Science Center Director, in a written statement. “While NOAA remains concerned that this population is not showing signs of recovery, at this time we do not believe this estimate represents a marked decrease in the population.”

Federal scientists suspect an actual population decline of 20 percent would result in more reported deaths. On average over the last 10 years, 9.8 beluga carcasses have been reported annually.

Another factor throwing the estimate into question is that survey conditions changed for the 2011 count. For example, scientists used a different plane, changing the viewing ability of observers. Also, whales may have spent more time under water feeding — they’re usually dining on the tail end of the eulachon run in late June, said Rod Hobbs, a NOAA biologist who plans and analyzes the survey.

Despite the uncertainty, NOAA said in a written statement the estimate falls within the range of the 10-year population trend for Cook Inlet beluga whales, which shows an average annual decline of 1.1 percent. NOAA began surveying the white whales in 1993, when the survey counted 653 animals. The lowest survey came in 2005 with 278 animals — a 57 percent decline in a dozen years.

The June aerial surveys, relying on video images and observer counts, are conducted by scientists with NOAA’s Alaska Fisheries Science Center.

Douglas Vincent-Lang, Alaska’s Endangered Species Act coordinator, said the state has not determined its next step following the November ruling by Royce Lamberth, chief of the U.S. District Court in Washington, D.C., which upheld the beluga’s endangered listing. Vincent-Lang said on Monday he hadn’t had a chance to review the 2011 survey and analysis yet, which is available here.

But he said that the state generally has problems with the estimates because, while NOAA is likely using the best science available, counting whales is extremely difficult. The 1.5-ton mammals are often beneath the surface and difficult to distinguish from one another when they rise to the surface. Each estimate comes with a large margin of error, which means hundreds of whales may be overlooked.

 

Source: ALASKA Dispatch

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~ by FSVSF Admin on 25 January, 2012.

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