What's killing belugas?

Photo: The Canadian Press

A federal plan for the recovery of endangered Alaska beluga whales calls for a reduction in threats of high concern while scientists try to pinpoint what has kept the population from growing.

The National Oceanic and Atmospheric Administration on Wednesday announced its recovery plan for Cook Inlet beluga whales, a population listed as endangered since 2008.

NOAA's National Marine Fisheries Service acknowledges it does not know why the population hasn't bounced back. In the absence of an answer, the agency will focus on research and potential threats, such as noise and the cumulative effects of "multiple stressors."

"Until we know which threats are limiting this species' recovery, the strategy of this recovery plan is to focus recovery efforts on threats identified as of medium or high relative concern," the agency said.

A 1979 survey counted nearly 1,300 beluga whales. A 2014 survey estimated just 340 and a population continuing to trend downward.

The agency identified 10 potential threats to belugas. Of highest concern are catastrophic events, such as natural disasters or oil spills; cumulative effects of multiple stressors; and noise.

Threats of medium concern include disease agents, such as blooms of harmful algae, loss of habitat, a reduction in prey and unauthorized killing.

Threats of relatively low concern include pollution, predation and subsistence hunting.