ANCHORAGE (AP) -- When pilot Glen Ballard guided his Era Aviation helicopter about 500 feet above frigid Cook Inlet last week, he was startled by unexpected motion among shifting ice pans near the Monopod oil production platform.
At least three beluga whales were thrashing about and rising to breathe.
''They were between floats of ice,'' he said. ''They were just rolling on the surface like they might be feeding on something.''
The sighting, near Trading Bay about 60 miles southwest of Anchorage, offered another bit of evidence that local beluga whales spend winters roaming the same upper Cook Inlet waters where they chase the summer's salmon and hooligan.
The presence of the belugas in what appears to be ice-choked, fish-free desolation raises more than a few fundamental questions about upper Inlet winter habitat, according to federal biologists.
Such as: What are the whales eating out there?
''As we have been told by the Native hunters in all locations in Alaska, where you'll find belugas is where you'll find food,'' said beluga management biologist Barbara Mahoney of the National Marine Fisheries Service in Anchorage.
Six local belugas tracked with satellite tags have spent the past three months sticking close to home in a pattern first documented in two tagged whales last year.
''We're finding it very fascinating in terms of their movements or what people would say is their non-movements,'' Mahoney said. ''They're still moving back and forth, working the Inlet between Knik and Turnagain arms and west of Fire Island ... Knik and Turnagain arms are very important to them.''
The genetically isolated belugas may have once numbered more than 1,300 throughout Cook Inlet but had crashed to an estimated 347 by 1998 and now are thought to number between 350 and 450.
Federal biologists blamed the decline on overhunting by Alaska Natives. In a step that allowed the fisheries agency to regulate future hunts, the whales were listed as depleted under the Marine Mammal Protection Act.
But a coalition of environmental groups and lifelong hunter Joel Blatchford have argued that factors including oil development, commercial fishing, urbanization, shipping, noise and pollution could harm the whales and must be scrutinized under the more stringent Endangered Species Act.
U.S. District Court Judge James Robertson of Washington, D.C. rejected the suit in August. The U.S. Court of Appeals will consider the matter this year.
Federal biologists say counts during the past two seasons suggested that the decline may have bottomed out. The abundance estimate for 2001 will probably be released next month, according to Rod Hobbs of the National Marine Mammal Laboratory in Seattle.
One critical step in planning any recovery has been finding the whales' winter destination. Last year, two tagged belugas surprised biologists by remaining in the upper Inlet until the tags stopped signaling in early January.
In September, biologists captured and released seven whales with tracking tags expected to last through next summer. Six tags have been generating regular signals.
A few whales wandered south, including one that nosed into Chinitna Bay on the west side of the Cook Inlet across from Anchor Point. But by November, the tagged belugas had returned north and appeared to be swimming within 10 to 20 miles of Anchorage.
One wandered up Knik Arm to Eagle Bay and another moved up Turnagain Arm east of Girdwood. Many whales spent weeks meandering through Chickaloon Bay on the north coast of the Kenai Peninsula.
In December, the six tagged whales began haunting the open Inlet west of Anchorage, generating some hits in the same area as the sighting near Monopod. Many hits were in deeper water in the middle of the Inlet.
''They're probably avoiding the heavy ice that's built up in the arms,'' Hobbs said.
In one attempt to track what belugas eat, scientists have begun gathering fish samples. Fatty acids from certain prey species remain in beluga tissue, allowing scientists to catalog what that whale had for a recent meal. But the project requires detailed chemical analysis of 100 prey species and subspecies and will take years to compile, Hobbs said.
Another way to uncover secrets of whale cuisine is more direct. In summer, the scientists have started sampling near beluga groups with a 200-foot gillnet that has different mesh sizes aimed at snaring different kinds of fish.
''It's opportunistic sampling,'' Hobbs said. ''We've found salmon and hooligan.''
Finding out what the whales might be eating, if anything, during winter is much harder because of floating ice, bad weather and the difficulty of finding belugas by boat. A winter sampling trip will take years to arrange.
In summer, helicopter pilots often see whales in Inlet southwest of Anchorage, said Lash Larew, Era's executive vice president and veteran helicopter pilot. Big pods gather in sync with salmon runs at river mouths, signaling that the fish are in.
Winter sightings suggest something similar, he said.
''They've got to be feeding on something,'' Larew said. ''They stay where the food is. They're smart.''
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