Marc Donadieu/Turnagain Times
A beluga whale briefly surfaces while searching for fish in Turnagain Arm near Girdwood.
By Marc Donadieu
Turnagain Times Correspondent
Throughout the summer, researchers have been conducting studies on the endangered population of Cook Inlet beluga whales. Researchers are learning more about the beluga whale diet, their reproductive capacity, current population numbers and background noise levels that may affect their habitat.
The Cook Inlet beluga, which was declared endangered in 2008, is genetically distinct and geographically isolated. According to a survey conducted by the National Oceanic and Atmospheric Administration Alaska Fisheries Science Center, the Cook Inlet beluga population numbers decreased dramatically in the 1990s.
In the 1970s there were an estimated 1,300 Cook Inlet beluga whales, but in the 1990s they declined dramatically. Based on a 2012 survey, the current estimate of the beluga population is 325 whales. The results of this year’s biannual survey are still being calculated.
“We did the 2014 June abundance surveys,” said Barbara Mahoney, a biologist for the National Marine Fisheries Service Protected Resources Division. “The abundance estimates will come out after the new year. That’s because the folks in the lab are looking at the videos.”
Video surveys are conducted by flying along the coast of Cook Inlet and through its middle in search of beluga whales. Weather conditions can impact how much gets documented during the biannual survey.
“This year the survey days for the lower inlet were fantastic,” said Mahoney. “I’m pretty sure they got 100 percent coverage. Sometimes, if the weather is really windy or bad, they can’t see if it’s a white whale or a white wave.”
During the June survey, whales were seen in the upper parts of Cook Inlet.
“We saw no whales below Tyonek this year,” Mahoney said. They were up at the Susitna and Little Susitna Rivers, Knik, and a little bit were in Turnagain Arm and Chickaloon Bay.”
The number of beluga calves born this year is unknown since the abundance survey was conducted in June, and belugas usually calve around July and August. Knowledge about beluga calving is obtained by examining deceased, pregnant females.
“The latest pregnant female we had was July 4,” said Mahoney. “We had a dead whale that was pregnant that washed up. We’ve had them in June, May, and one in early April. They obviously aren’t as fully developed in the earlier months.”
Another form of research being conducted is analyzing beluga bones and teeth at the molecular level to determine their diet by looking for stable isotopes.
“They’ll analyze the bones from individual whales for carbon and nitrogen isotope signatures so you can tell about the diet of the animal prior to when it died,” Mahoney said. “That’s not like fieldwork out in Cook Inlet as much as working with the museum and anybody with registered beluga whale hard parts.
“Looking at this isotopic signature,” she said, “you can look at the potential differences of diet by gender and age as well as the trophic level it’s feeding on. If they look at the isotopes related to teeth, then they can give the age of the specific animal. For example, if a beluga whale is predominantly feeding on fish one year and invertebrates the next year, that would be evident by using isotope analysis.”
When a stranded beluga dies or a dead one washes up on shore, it’s an opportunity to gather scientific data. A constant question is what the whale was eating.
“I check any stranded/dead belugas where we can look at the stomachs,” Mahoney said. “We’re looking specifically how many fish are in the stomach at that time, how many odalisks [ear bones] or fish bones are identified separately that the whale ate.”
In addition to checking stomach contents, the ovaries are removed from deceased female belugas.
“We had someone looking at reproduction, looking at the ovaries of females,” said Mahoney, “and we’ll have that report hopefully done this fall as well. We’ll get a better picture of their reproductive history by looking at a limited set of ovaries.”
Examining the ovaries yields useful information about the reproductive history of the individual whale. When this data is included with samples from other ovaries, reproductive trends of the Cook Inlet beluga population can be analyzed.
“It’s a good picture of the reproduction information we have for Cook Inlet,” Mahoney said. “So we can tell their age and see the scars from the pregnancy and know how many pregnancies they have had.”
Beluga whales have sensitive hearing. They communicate using a variety of sounds and use echolocation to feed, which is necessary when looking for fish in the murky, silt-laden water of Cook Inlet and Turnagain Arm.
“We also funded acoustic work in Cook Inlet,” Mahoney said. “We hope to have some reports due this fall related to some earlier studies with the environmental acoustic recorders that were placed in the inlet to measure some background noise to identify the noise habitat where the whales are found.”
The extent to which loud noise levels affect belugas is unknown.
“We don’t know how human activities are impacting them,” said Rod Hobbs, lead scientist for the Cook Inlet Beluga Project for the NMFS. “We know that cetaceans are sensitive to noise in various forms such as pile driving and ship noise. There are seismic surveys going on in the inlet. All of those are noise sources that could impact belugas. We don’t know to what extent.”
Beluga whale research in Cook Inlet is an ongoing project with many facets. There is still much to be learned about this endangered population.
“What we need to do now is more hands on research,” Hobbs said. “Looking at reproductive success, looking at prevalence of disease and their physical condition at the beginning and end of summer to see if feeding is an issue. A lot of those sorts of research are fairly easy to do on terrestrial animals, but on belugas they are quite difficult because you have to capture them. You have to hold them for a period of time with a veterinarian.”
Funding research is always an issue, yet there is a lot to be learned by conducting more ambitious projects about beluga whales.
“The best example we have is the project in Bristol Bay,” Hobbs said. “It takes about $300,000 to do 10 whales a year to do all of the analysis and samples collecting associated with it. For Cook Inlet, the fisheries service has been very reluctant to do captures like that until we have a good idea how to ensure that the captured whales aren’t injured. The project in Bristol Bay is certainly a good trial project for that.”
And details of this research on live beluga whales provide a lot of valuable data.
“The successful method we developed was that we would circle the whale with a net,” Hobbs said. “You approach a group of whales. You find one that’s by itself. A boat quickly runs a circle around the whale, dropping a net that’s about 800 feet long. Then you wait until the animal becomes entangled in the net.
“Then we approach it with zodiacs, rubber boats, so there are no hard edges that are injuring the whale. We take the whale out of the net and put it into a sling that supports it between two boats. And then we do the various health assessments or tag attachment with the whale.”
A team of researchers worked around the Nushagak River last year.
“It takes a couple of hours to draw blood, assess hearing, measure the blubber thickness and things like that,” Hobbs said. “A project like that would allow us to begin to see how the belugas in Cook Inlet maybe differ from a population of healthier belugas like in Bristol Bay, which is increasing at the moment.”
In order to learn more about the belugas, tissue samples need to be collected from live ones. Since live captures are not being conducted, another technique is used.
“Our current plan,” said Hobbs, “is a project in which we begin to collect biopsies. In this case, we use a dart that collects a little bit of skin and blubber, and that doesn’t give us all of the information you can gather from a held assessment, but it gives you some basic information on genetics and reproductive hormones, which can tell you if they’re pregnant or not and if it’s a female or male. If you find out a female is pregnant, then you can go back a year later, using the photo identification and see if she gave birth, and that would give you a measure of reproductive success.”
When the biopsies are analyzed, they offer a lot of information for researchers to assess the health of the beluga population.
“If you look at the stress hormones that are present in the blubber,” Hobbs said, “a lot of hormones remain in the blubber because they’re soluble in fat, and they build up in the blubber. You can get an idea what the hormone levels are in the blood, which are more commonly used in health studies. You can look at the stress hormones and compare that to similar stress hormone levels in other populations and see if maybe they’re under a chronic stress or not.
“A good example of that occurred in right whales on the East Coast. In the week after the attacks on 9/11, all of the shipping was stopped on the East Coast for a week. And during that week, they had samples that were collected from right whales, and they saw changes in these stress related hormones in the blubber, which gave them an idea how much something like noise, for instance, affected the whales. We’re looking at starting a project like that next summer.”
As to why Cook Inlet beluga whales keep dwindling in number, there are no easy or obvious answers. Research suggests it is a combination of factors.
“There are a lot of different possibilities,” said Hobbs. One could be changes in the amount of food that is available to them such as anadromous fish runs like salmon and hooligan. Or it could be a change in their winter-feeding. They seem to depend on the food they can find in the winter. We don’t know much about changes in the available forage, if there have been. So food is certainly one question that hasn’t been resolved.
“There have been changes in their habitat, such as salmon streams that are available to them. There are changes in the inlet. There are a number of open possibilities that we haven’t been able to sort through.”
The big question is can the endangered Cook Inlet beluga whale population recover? That is what researchers are trying to answer and to discover what, if anything, can be done to assist this endangered species.
“I think it can recover,” Hobbs said, “but we don’t know why it’s not recovering. So that’s the difficult question at the moment. I think it can recover if we can figure out how to change its circumstances. We don’t know what we need to do to help it recover.”