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NMFS survey shows low beluga count Fisheries Service says Cook Inlet population still not showing signs of recovery despite subsistence hunting quotas since 1999 Alan Bailey Petroleum News
The latest NOAA National Marine Fisheries Service annual survey of Cook Inlet beluga whales, carried out in early June, has estimated a whale population of 321. This figure is lower than the count of 375 from the 2008 NMFS survey and is likely a disappointment to those hoping to find solid evidence of a recovery in the beluga population, while lending support to those who back the October 2008 NMFS decision to list the whales as endangered.
“The endangered Cook Inlet beluga whale population is not showing recovery, according to NOAA Fisheries Service’s latest annual survey and estimate,” NMFS said Oct. 6. “NOAA scientists, analyzing recent population estimates, find a continued trend of gradual population decline.”
Although beluga whale populations exist in several regions around the coast of Alaska, the whales in the Cook Inlet form what NMFS terms a “distinct population segment,” in effect a subspecies that is isolated from beluga populations elsewhere.
Surveys since 1993 Since 1993 NOAA scientists have conducted a beluga population survey each June by spending several days flying over upper Cook Inlet, counting the whales. Photographs and videos of whale groups supplement the aerial observations. Statistical methods are applied to account for whales that are out of sight under the water, and to extrapolate detailed counts to aggregations of whales observed from the air. The end result is an estimate of the total whale population for the whole of Cook Inlet, together with an estimate of the level of uncertainty in the whale count.
A precipitous drop in the whale population, as counted in the 1990s, appeared to result from unsustainable levels of subsistence hunting at that time and triggered the introduction of hunting regulation in 1998. Since regulation came into force, subsistence hunters have harvested just five whales.
But, with NMFS saying that the continuing surveys have not shown any recovery in the whale population since the start of hunting regulation, the agency listed the whales as endangered, a controversial decision that raised major concerns about potential impacts on economic activity in the region while attracting praise from environmental organizations.
Critical habitat As required by the listing, NMFS is scheduled to propose designated areas of critical habitat for the whales at the end of October. The location and nature of that habitat will in part determine how government regulators will assess the potential impact of various local activities on the whales, with the ESA listing of the whales perhaps affecting activities that include oil and gas exploration, proposed tidal power developments, Port of Anchorage expansion and wastewater treatment in Anchorage.
Those opposed to the beluga whale listing have proposed alternative approaches to conserving the whales and have questioned the NMFS survey results. Some have said that the surveys undercount the juvenile whale population, because the grey color of the whales makes them difficult to spot in the water. NMFS, on the other hand, has upheld its survey methods as reliable.
Some of the questions over the surveys relate to the manner in which the data are interpreted. NMFS, having used the data to plot a trend line for the population since 1999, says that the trend shows an average rate of population decline of 1.49 percent per year.
Trend meaningless But since the confidence limits for the survey results for every year that the survey has been carried out overlap with each other, the determination of a trend from the data is meaningless, Jason Brune, executive director of the Resource Development Council, told Petroleum News Oct. 12.
“If you look at the error bars, statistically today’s population is no different from 1994’s population,” Brune said. “The error bars are overlapping.”
Moreover, Beluga specialist L.K. Litzky has published a paper saying that it would take about six years for the beluga population to start to recover from the overharvesting of the whales in the 1990s, Brune said. Litzky’s finding is consistent with an apparent population minimum of 278, determined by the 2005 NMFS survey, he said.
And the population trend derived from the survey data depends on the range of years chosen for the trend determination.
“If you look, since 2005 the number has shown growth,” he said. “… So depending on where you start from you can either show a decline or an increase. … Statistics can show what you want them to show.”
More research Many RDC members have reported seeing an increased number of Beluga whales in the past year, Brune said. And determining what is happening to the Cook Inlet whales needs more research than just one survey per year, he said.
Brune praised research being done by LGL Research Associates, identifying individual beluga whales in the inlet. In December LGL will publish its estimate of the beluga population size, Brune said.
“That’s the kind of science that we need to see being done, that will supplement this annual survey,” Brune said. “… We are very supportive of more research dollars. We’re supportive of as much science as can be done. My members have contributed a lot to those studies that have been done.”
Doug DeMaster, director of the Alaska Fisheries Science Center in NOAA Fisheries, told Petroleum News Oct. 13 that he agrees that the levels of uncertainty in the survey data make it impossible to derive a statistically significant population trend from the data. He also said that the NMFS population model does support the likelihood of a lag of a few years for the beluga population to start recovering from overhunting.
But arbitrarily picking a year such as 2005 as a starting point for a trend analysis introduces an unjustified statistical bias into the trend calculation — it is possible to engineer a trend simply by picking an appropriate range of years, DeMaster said.
No increase seen The key point is that NMFS beluga population modeling has indicated that the beluga population ought to increase at a rate of at least 2 percent per year, once the recovery of the population starts, but so far there is no evidence from the survey data of that happening, DeMaster said.
“Given the data, it’s unlikely that the population is growing at 2 percent or greater per year,” he said. “… We were obviously disappointed with the 321 number. We would love to have seen something higher.”
It might take a couple of years of higher numbers for it to be possible to infer a population increase, he said.
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