Estimated Abundance and Trend in Aerial Counts of Beluga Whales in Cook Inlet, Alaska, 1994–2012

Aerial surveys of beluga whales (Delphinapterus leucas) have been conducted annually in Cook Inlet, Alaska from 1993 to 2012. Beluga whales were seen near the coast and within river mouths in all years, with nearly all of the sightings in the northernmost portions of the inlet after 2000.

In this paper, we revisit abundance estimates from 1994 to 2012 and present changes in methods and statistical analyses that have occurred since an earlier publication in 2000. Our objectives include:

• a reanalysis of the abundance estimates over the 19-year aerial survey time series (1994 to 2012)
• revising the population trajectory through 2012
• estimating population trend rates for endangered Cook Inlet beluga whales

Annual surveys documented a decline of nearly 50 percent between 1994 and 1998 from an estimated 653 (CV = 0.24) whales to 347 (CV = 0.17) whales. With a very limited hunt (five whales total taken between 1999 and 2012), the anticipated recovery at a rate of at least 2 percent per year did not materialize. Instead, from 1999 to 2012, the rate of decline has been -1.60 percent per year, with a 97 percent probability that the growth rate is declining (i.e., less than zero) and a 99.9 percent probability that the growth rate is less than +2 percent per year.

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Roderick C. Hobbs, Kim E. W. Shelden, David J. Rugh, Christy L. Sims, Janice M. Waite. Published in Marine Fisheries Review 77(1), 2015. dx.doi.org/10.7755/MFR.77.1.2