Identifying Essential Summer Habitat of the Endangered Beluga Whale in Cook Inlet, Alaska

In response to the critically low numbers of beluga whales (Delphinapterus leucas) in Cook Inlet, Alaska, the U.S. federal government listed this isolated population as endangered in 2008. Despite the curtailment of subsistence hunting in 1999, the abundance of Cook Inlet belugas has remained low (less than 400 whales), with no obvious signs of recovery. As habitat is a critical component of population variability, our goal was to identify habitat selected by beluga whales. We developed predictive habitat models from the distribution and group size of beluga whales observed between 1994 and 2008. We fit a two-part hurdle model to describe the physical and anthropogenic factors that influence beluga presence (mixed model logistic regression) and beluga count data (mixed model Poisson regression). Beluga presence was negatively associated with sources of anthropogenic disturbance and positively associated with fish availability and access to tidal flats and sandy substrate. Beluga group size was positively associated with tidal flats and proxies for seasonally available fish. We produced habitat maps for beluga presence, group size, and the expected number of belugas in each 1 km² cell of Cook Inlet. These maps distinguish suitable habitat which could prove integral to the sustainability and recovery of the Cook Inlet beluga whale population.

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Kimberly T. Goetz, Robert A. Montgomery, Jay M. Ver Hoef, Roderick C. Hobbs, and Devin S. Johnson. Published in Endangered Species Research Vol. 16:135–147, 2012.