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Cook Inlet belugas: decline or not? The question of whether or not the beluga whales are heading for extinction revolves around the reliability of population data Alan Bailey Petroleum News
It seems that everyone involved in the debate about the U.S. National Marine Fisheries Service’s proposed listing of the Cook Inlet beluga whales as an endangered species wants to see the population of these playful animals recover. But does recovery require management of the animals under the Endangered Species Act?
The listing proposal stems from projections of beluga population statistics derived from NMFS Cook Inlet beluga survey data. And, as we reported in the April 29 edition of Petroleum News, some industry groups have questioned that data.
Although a 1979 survey estimated a population of 1,293 belugas, systematic counting of the whales did not begin until 1993, since when NMFS has conducted annual aerial surveys. The aerial surveys estimated a decline in population from 653 whales in 1994 to 347 whales in 1998. That decline proved particularly severe in the 1990s, as a result, most people seem to agree, of unsustainably high levels of subsistence harvesting of the whales.
Regulation of hunting Regulation of subsistence hunting of the whales since 1998 and cooperative efforts between Native hunters and NMFS have dramatically cut the harvest to just eight whales over the entire period since regulation began.
So, has the reduction in hunting resulted in a recovery of the beluga population? NMFS had estimated that regulation of the subsistence harvest would result in a population recovery of between 2 and 6 percent per year.
But the 2006 NMFS survey estimated a population of 302 whales, suggesting a continuing population decline rather than the expected rebound.
However, Jason Brune, executive director of the Resource Development Council, has told Petroleum News that a beluga survey funded by Chevron shows that the NMFS data underestimate the population size.
Chevron spokeswoman Roxanne Sinz told Petroleum News May 3 that the Chevron survey, conducted in the summer and fall of 2005 and 2006, set out to build an identification catalogue of the whales, and to “examine the abundance, behavior and population characteristics of beluga whales in upper Cook Inlet.” The researchers identified individual whales from the whales’ physical characteristics, using photographs taken during 132 whale encounters involving 99 surveys in the Knik Arm, in the Susitna Flats and from road sightings along Turnagain Arm (the researchers have not yet completed the cataloguing of the 2006 photographs).
By distinguishing and identifying individual whales, the researchers counted a total of 350 animals. That count is larger that the NMFS estimate but may nevertheless underestimate the total population: the Chevron research only surveyed part of the Cook Inlet beluga geographic range and the researchers have not attempted to extrapolate their findings to a total population count for the inlet.
The Chevron research found that approximately 43 percent of the beluga population had not reached maturity, Sinz said.
“The high percentage of sub-adults indicates not only a healthy population but one that is recovering,” Sinz said.
Sinz also commented that it is “extremely difficult to see the sub-adult beluga whales from the air because they remain grey in color from birth to about eight years.”
And, according to a letter from the Resource Development Council to NMFS, in response to the proposed beluga listing, “It is obvious that juvenile belugas, which match perfectly with the color of Cook Inlet waters, are impossible to see and subsequently count from an airplane.”
NMFS response “It is true that they are difficult to see, but we have ways of dealing with that,” Rod Hobbs, leader of the beluga project at the national marine mammal laboratory of the National Atmospheric and Oceanic Administration, told Petroleum News on April 30.
Hobbs explained that the researchers conduct the NMFS surveys on summer days when conditions enable observations around the entire survey area — upper Cook Inlet, Knik Arm and Turnagain Arm. Surveys take place at low tide, when the area of water that needs to be traversed is at a minimum.
When a beluga pod is spotted the survey aircraft makes eight to 16 passes parallel to the direction of movement of the whales, shooting video of the animals. One video camera films the entire pod, while a second video camera zooms in on details within the pod. The video images provide a recorded means of counting the whales, while observers on the aircraft also conduct counts during the flights.
It is possible to see juvenile whales in the close-up video but not in the video that shoots the broader picture, Hobbs said. When analyzing the video images, the researchers match up the whales that appear in both the close-up and broader images. They then count the whales that are only visible in the close-up image and extrapolate that count to make an estimate of the total number of belugas in the complete pod. The estimates of whale numbers also factor in the likelihood that some whales have dived under the water.
And Hobbs said that it is possible to spot whales in the water from the air using factors other than skin color.
“They have a smooth and shiny skin, so they do look distinct,” Hobbs said, adding that whales on the surface tend to cast distinctive oval shadows, depending on the angle of the sun.
And the color of the water is not uniform, he said.
“There are areas in the Inlet where the grey scale of the water is close to that of the (juvenile) whales,” Hobbs said. “However, in general the water is more of a brown color.”
Complete population? Brune also said that, because little is known about where the whales go at different times of the year, annual surveys could easily miss some significant component of the population that is outside the survey area.
But Hobbs said that NMFS researchers had reviewed hundreds of hours of surveys from the Gulf of Alaska.
“It is unlikely that there are large numbers of belugas missed that are outside the (Cook Inlet survey) area,” Hobbs said.
Brune also thinks that it is too early to determine that the beluga population is declining, especially given the very long beluga whale gestation period. And running a population model using uncertain and underestimated population data results in meaningless projections — NMFS population estimates involve high levels of uncertainty, he said.
But Hobbs said that the NMFS population model used to project future Cook Inlet whale populations includes the known characteristics of the beluga whale life cycle and factors in the uncertainties in the population census. The model was run using the first age of reproduction set one-third at five years, one-third at six years and one-third at seven years, he said.
That model found a 65 percent probability that the population would continue to decline — increasing the initial age of reproduction does not result in a major degradation in that statistic.
“If you change that to 10 years it doesn’t make much difference,” Hobbs said.
The model also predicted a 26 percent probability of extinction of the Cook Inlet belugas within 100 years. That 26 percent probability greatly exceeds the NMFS criterion of a 1 percent probability that triggers an endangered species classification.
However, Hobbs said that the national marine mammal laboratory scientists are in the process of reviewing video from the annual surveys to determine trends in the population of juvenile whales.
“We’re looking back through our zoomed video to see if we can get a count on the ratio of juveniles to adults (over time),” Hobbs said.
Continued MMPA regulation? RDC has said that the regulation of the beluga whale stock should continue under a categorization as depleted under the Marine Mammal Protection Act, rather than be listed under the Endangered Species Act. The MMPA depleted categorization, established in 2000, has resulted in a draft Cook Inlet beluga whale conservation plan. But that plan has never been implemented, Brune said.
NMFS has said that the conservation plan remains unfunded and, as a consequence, may not be activated.
But an ESA listing “so soon after NMFS’ original designation under MMPA and subsequent court approval, will only lead to additional burden on economic and community development activities in and around Cook Inlet with no clear, corresponding benefit to the stock,” RDC said.
Brune also said that more research is needed into the factors that impact the beluga population — the existence of a thriving beluga population during the heyday of Cook Inlet oil exploration indicates that this type of industrial activity does not impact the whales, he said.
“We’ve been agitating for more research on these animals for years,” Brune said.
Hobbs said that NMFS is looking for ways to do more research.
But with the survey data and the population model pointing to a beluga population in trouble, NMFS has no option but to seek listing of the whales under the Endangered Species Act, regardless of why a population decline may be happening, Hobbs said.
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