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Getting to know the belugas Research team has been able to identify 188 individual Cook Inlet beluga whales and is learning much about these elusive animals Alan Bailey Petroleum News
To the untrained eye, one beluga whale in Alaska’s Cook Inlet looks very much like another — a white, torpedo-shaped body with a bulbous forehead moving through the grey waters of the inlet. But look more closely, and many of these playful animals have faint but distinct patterns of whitish scar remnants that enable individual identification.
Scientists from LGL Alaska Research Associates are using these marks to identify belugas in the upper Cook Inlet and to monitor the movements of those whales. Chevron, ConocoPhillips and the National Fish and Wildlife Foundation are sponsoring the study, while LGL is contributing research facilities and staff.
Information about the Cook Inlet beluga whales is of heightened interest because of a proposal by the National Marine Fisheries Service to list the whales as an endangered species — using the results of annual aerial surveys, NMFS has predicted a 26 percent probability of extinction of the Cook Inlet belugas within 100 years.
But some people have questioned the reliability of the NMFS survey data and have said that the whale population is likely to be recovering, following the regulation of beluga subsistence hunting in 1998.
On Jan. 18, Dr. Tamara McGuire, project manager for the study, and Chris Kaplan, lead biologist, talked to Petroleum News about the LGL research project and its findings to date.
Started in 2005 Since the project commenced in 2005 the scientists involved in the study have had to devise and refine techniques for finding and identifying individual whales, McGuire explained. The observers use a digital camera to record pictures of the whales, while modern computer technology helps with whale marking assessment and cataloguing.
“The challenge was getting a photograph (of a whale) with no dorsal fin, that is very low in the (turbid) water, and we were picking up white marks on mostly white whales,” McGuire said. “… It takes quite a bit of time and training to be able to know what kind of marks are actually the ones that we need to be tracking all the time.”
“We learned that these white marks are the ones that really show up and they’re marks that are deep and lasting,” Kaplan said. “… Once you learn to look for (the marks) … I think they’re really clear and obvious.”
One issue that the team has had to contend with is that a beluga whale has a relatively long body, only parts of which will emerge above the water surface at any one time. As a consequence different sections of that body may be photographed at different times and then be incorrectly identified as several different whales.
So, the team has had to painstakingly match the head, middle and tail sections of individual whales from hundreds of photographs. Several researchers review the matching of the marks — if there is disagreement about a match, that match is discarded, McGuire said.
“It’s only when we get all three (sections) of an animal that we’re going to call it an individual,” McGuire said,
And on that basis the team has now obtained complete identification profiles on 188 whales.
Calves The researchers have also learned to spot calves in the photographs — the calves are grey in color and can be difficult to pick out against the water.
“We have individuals … we’ve ID’d from their marks and we’ve seen them with calves year after year,” McGuire said. “… That’s been exciting to be able to track moms, where they travel.”
One of the calves is now exhibiting the marks that the researchers use for identification; so the team should be able to determine when that calf leaves its mother and, perhaps, whether it leaves its mother when she has her next calf, McGuire said.
But what do the research team’s findings mean in terms of the total population of Cook Inlet belugas?
It’s difficult to compare the results of the LGL research with the NMFS survey data, because the two surveys are using completely different methods. The LGL project is identifying individual whales at specific locations over multiple years, while NMFS is trying to take a snapshot count of the whales from the air at the same time each year across the entire upper Cook Inlet region.
To obtain a population estimate from the LGL data, the scientist will first have to allow for the inaccuracies in identifying individual whales, by assessing the ease with which each individual whale can be identified.
“Some whales are well marked, and some have no markings at all,” Kaplan said.
The assessment of the quality of the matches would then lead to a calculation of the statistical confidence limits for the whale count.
“That’s where it gets really tricky to do that population estimate, and that all has to be done first,” McGuire said.
In addition the research cannot at this point shed any light on the total number of juvenile whales in the Cook Inlet, or whether the juvenile population is increasing or decreasing, McGuire said.
Known locations There’s also the question of how much of the total beluga population visits the sites that the LGL team uses for its observations.
The team specifically goes to sites where it knows it will find whales. For example, whales can be found at the Susitna Flats in June and it is possible to predict very accurately the time when whales will pass a particular point in Turnagain Arm, McGuire said.
“We really do know where to go now to find the whales,” McGuire said. “… The largest group we’ve seen at one time was 101, so we know we’re not looking at the entire population at once.”
Combining the surface observations of the whales with some aerial surveying might enable a better understanding of the total number of whales in an area at any one time, she said.
But even without aerial surveys, determining whether the whale count levels off at some maximum over several years should shed some light on the migratory habits of the whales — a number much lower than the NMFS population estimate would suggest that only part of the total population visits the research sites, for example.
Surprising observations The LGL team has already made some surprising observations. In particular, the scientists have observed grey-colored adult females with calves, thus demonstrating that, contrary to popular belief, the whales do not all become white when they mature.
“A third of the moms that we’ve seen are actually grey,” McGuire said.
In fact the team hopes to be able to use observations of whales that were tagged by NMFS several years ago to relate whale color changes to the known approximate ages of the animals.
“I suspect there’s a lot of variability here,” McGuire said.
But having identified numerous individual whales, the research team has started tracking the movements within the upper Cook Inlet of those individuals. That may ultimately lead to insights into life-cycle information such as calving areas and the seasonality of calving.
“We’re able to track them around through the seasons we’re out there, and through the locations,” McGuire said. “There are a number of them that we’ve been able to identify as mothers with calves. … So we’re really getting to the more interesting bits now.”
And, having cracked the code of identifying the whales, the team feels ready to start addressing some of the big questions such as the total size of the whale population, and whether that population is increasing or reducing.
“I think everyone was so excited about the results … because we were finally getting to what our goal is, which is learning more about the whales,” McGuire said. “… To be able to generate data and to be able to ask questions with it, as we see patterns in the data.”
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