Range Contraction in a Beluga Whale Population

The small, isolated population of beluga whales in Cook Inlet, Alaska has had a distinct contraction in range over the past three decades. This contraction is a function of a decline in abundance, evidently caused at least in part, by high takes during unregulated subsistence hunting. During the 1990s, hunting resulted in takes of over 50 whales in the northern portion of Cook Inlet. Concurrent with the decline in abundance, sightings became rare in the southern inlet, though human impact had been relatively low there. Curiously, the density of whales in the northern inlet remained high in spite of the hunts. Significant changes in beluga whale distribution are evident across three periods:

• 1978–1979 (the earliest well-documented data)
• 1993–1997 (during the recorded decline in abundance)
• 1998–2008 (when hunting was regulated and recovery was anticipated)

The center of the summer range of beluga whales contracted northeastward into upper Cook Inlet from the 1970s to the 1990s. This continued into the 2000s with a longitudinal shift toward Anchorage (the largest city and port in Alaska) occurring between the 1990s and 2000s. The result is a reduced range (>7000 to <3000 km²) in all but the area with the highest degree of human disturbance. If and when the Cook Inlet beluga whale population begins to increase, a reoccupation of peripheral habits may be the first indication of recovery.

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David J. Rugh, Kim E.W. Shelden, Roderick C. Hobbs. Published in Endangered Species Research Vol. 12: 69–75, 2010.