The number of beluga whales swimming in Cook Inlet appears to be increasing, but biologists say it's too soon to know whether the winsome white whales are finally making a comeback.
Fisheries biologists with the National Oceanic and Atmospheric Administration were quick to caution Tuesday that the increased estimate does not in itself prove that the genetically distinct whales are finally recovering after numbers fell by more than half — a drop blamed largely on overharvesting by Alaska Native subsistence hunters.
"While we are encouraged by this higher estimate, further surveys will be required to determine if this is a reliable upward population trend," said Doug DeMaster, director of the Alaska Fisheries Science Center in Seattle.
Over the years, the numbers gathered in the annual survey have shown a lot of variability, said Rod Hobbs, leader of the beluga whale research project at NOAA's National Marine Mammal Lab, also in Seattle.
Hobbs said the long view shows that this year's estimate of 375 beluga whales is about what it was in 1999.
"They are not that much different," Hobbs said. "We certainly need more survey work before we can be satisfied that they are actually increasing."
Debate over the beluga ranking
The white whales that swim the silty waters near Alaska's largest city are at the center of a debate over whether they should be listed as endangered under the federal Endangered Species Act. The National Marine Fisheries Service determined this year that if nothing changes Cook Inlet belugas are in danger of becoming extinct in the next 100 years.
In 2000, the agency refused to list the whales. A new listing decision is expected by the end of March. The agency is wading through over 100,000 public comments on the issue.
Gov. Sarah Palin already has come out against listing the whales because of the potential for long-term damage to the local economy. Listing also could affect some major projects proposed for Cook Inlet, including the building of a large coal mine across Cook Inlet from Anchorage and the building of a bridge across the Knik Arm.
In June, NOAA biologists flew five surveys of waters in the upper Cook Inlet where the whales tend to be most often and recorded video of the belugas in groups. The biologists came up with the new estimate of 375 whales — up from 302 whales last year — by examining the video and from counts made by researchers.
Researchers used two video cameras for the count. One is set up to zoom in on the center of the pods to capture images of young whales that are dark gray for the first few months after birth and hard to see in the silty water. That information is later used to account for the fraction of young whales likely missed in the overall count.
"The observers were counting more whales and there were more whales to see, either because they are spending more time on the surface or maybe there are more whales," Hobbs said.
Threats to beluga grow
An estimated 1,300 belugas swam the waters off Anchorage as recently as the 1980s. Numbers fell by nearly half between 1994 and 1999 when the average yearly subsistence harvest was 77 whales.
Alaska Native hunters, working with the federal government, agreed to cut back dramatically on the harvest to give the whales a chance to recover. Only five belugas have been killed for subsistence in Cook Inlet in the past eight years. No whales were taken this year.
Biologists initially believed that cutting back on the harvest would do the trick. But numbers for much of this decade have remained stagnant.
This year's increased estimate is the largest since 2001 when 386 whales were counted.
While good news, the higher estimate is no reason not to list Cook Inlet belugas, said Brendan Cummings, ocean programs director for the Center for Biological Diversity, which is leading the fight to get the ESA listing.
"The opponents may say this is a reason not to list the beluga ... but the threats to the species have only grown over time with increased industrialization of the inlet and the impacts of climate change," he said.