Teeth, noise, photos: Looking for clues about the ailing Cook Inlet beluga population

Nine years after Cook Inlet belugas were formally listed as endangered, the population is stuck at only about one-fourth of its historic size. Despite a series of protections, the belugas have not recovered, and exactly why remains a mystery.

Now, scientists are looking in some unusual places for answers: a trove of photographs collected over the past decade, data on beluga deaths contrasted with data from a beluga population thriving elsewhere in Alaska, the soundscapes beneath the Inlet's winter ice and the belugas' own teeth.

Two broad studies funded by grants from the National Oceanic and Atmospheric Administration are seeking answers about belugas' food — what they eat, where and when they eat it — and on the population structure, and how it compares to that of the healthy Bristol Bay population.

Both grants, announced last month, were made under a provision of the Endangered Species Act, and are augmented by funding from two nonprofit aquariums. The grants are paying for three-year studies led by the Alaska Department of Fish and Game and involving scientists from the University of Alaska Fairbanks and other institutions.

To learn more about belugas' foraging behavior and success, the scientists are drilling into the whales' teeth — literally.

Layers of the teeth accumulate year to year in belugas, and the result is a microscopic archive similar to tree rings, said Mat Wooller, a professor at UAF's College of Fisheries and Ocean Sciences and Water and Environmental Research Center.

"The really neat thing about the teeth is you can go back in time quite a long, long way," said Wooller, who is working on the project with a graduate student specializing in the subject.

The teeth are about the size of a human pinky. The array of layers is seen clearly when the teeth are cut lengthwise, Wooller said.

The story of the layers is told by the molecular weight of the elements contained in them. This part of the NOAA-funded foraging study stems from a master's thesis written by Mark Nelson, a Fairbanks-based Fish and Game wildlife technician who is pursuing graduate studies at UAF.

For his thesis, Nelson analyzed isotopes of elements contained within the teeth, using specimens pulled from dead belugas found on beaches or from whales harvested many years ago. The newest teeth in that collection are from the early 2000s, so there is a need for more specimens, said Wooller, who is Nelson's adviser.

Carbon and nitrogen isotopes reveal information about what they eat, and isotopes of strontium — a metallic element that has different signatures for saltwater and freshwater environments — reveal information about where they are finding their fishy food, Wooller said.

The goal is to use the teeth to try to understand changes in diet, foraging and body condition over the past 50 years.

To date, analysis has shown a shift from a wide dispersion around the Inlet to the to more freshwater-influenced areas, Wooller said. That parallels observations of a contraction in range, with belugas now clustering in summer near the mouth of the Susitna River and similar sites in the northern part of the Inlet.

The shifts in belugas' foraging merit further examination, Wooller said.

"They are changing the where. They must be changing some of the what as well," he said.

Movement from what is believed to have been an Inlet-wide distribution to a concentration in the river-influenced areas in the north is significant, but exactly why is unclear, said Mandy Keogh, a Fish and Game wildlife physiologist.

"We know that their habitat is somewhat restricted. What we don't know is why," Keogh said. Yet unknown is which came first — the population decline or the habitat shrinkage.

"We're not sure if it's a result of what's happening or if it's causing what's happening," she said.

Also unknown, she added, is where the belugas go in winter and what they eat during that season.

The other part of the foraging study seeks to use sound recordings to find the answers.

Scientists this fall are installing acoustic devices in various parts of the Inlet; the first deployment was in mid-September in the Chickaloon Bay area of the northern Kenai Peninsula, by the entrance to Turnagain Arm, and further work is planned for the Homer, Kenai and Anchorage areas.

From the whales' own mouths, scientists can learn whether the mammals are successful at finding food in winter, Keogh said. The belugas' whistling songs follow a specific pattern when they are foraging and using echolocation to communicate with each other; after they have eaten, they make a buzzing-type noise, she said.

The acoustic monitoring will also help explain what is happening in winter under the water's surface and, sometimes, under the ice, Keogh said.

It will record passing ships, whirring machines and other noises created by human activity. It will track marine mammals, like porpoises and killer whales, that might be sharing the belugas' territory. And it will measure background noises created by tides, waves and moving ice.

The latter is probably significant, Keogh said. "Even if you were to remove all of the human activity in the Inlet, it's not a quiet environment," she said.

The second grant-funded study seeks a better understanding of the Inlet beluga population structure, and what it should be, to start recovery.

To do that, scientists will be examining photographs of whales and data collected from beached carcasses to piece together male-female ratios, age distributions, mating behaviors and other characteristics of the Inlet population. They will compare that information to the biological data collected from Bristol Bay belugas and see if there are big differences.

"We're looking at a normal, healthy, growing population to see what that should look like," Keogh said.

There is plenty of data on dead Inlet belugas and living Bristol Bay belugas, along with a good collection of photographs that can be put to use, she said.

The Inlet beluga population crashed in the 1990s, which wildlife managers have said was likely the result of overhunting by the region's Alaska Natives. The hunts largely ceased at the end of the 1990s.

In 2008, the population was listed as endangered, and critical habitat was designated in 2011. Inlet beluga numbers have been hovering for years at about 340, a shadow of the former abundance of 1,300 animals.

The NOAA grants for beluga research were made under the agency's Species Recovery Grants to States program. NOAA has provided $850,641 for the study of foraging and diet and $414,742 for the population analysis. The grants cover all three years of the studies.

The state of Alaska sued in 2010 under Gov. Sean Parnell to stop the endangered species listing of Inlet belugas but, after contracting for attorneys in Washington, D.C., and Salt Lake City, lost the case the next year.