• Fifty years of Cook Inlet beluga whale ecology: recorded as isotopes (C,N,Sr) in their bone and teeth
    • Mark Nelson (Candidate for MS Marine Biology UAF & AK Dept. of Fish and Game)
    • October 28, 2016

Abstract

The endangered beluga whales (Delphinapterus leucas) in Cook Inlet are an important cultural and subsistence resource to coastal Alaska Natives and to the Cook Inlet ecosystem as a top-level predator. To better understand the past feeding ecology of beluga whales from Cook Inlet, we sampled bone (n=20) and annual growth layer groups (GLG; n=412) in teeth (n=26) for isotopic analyses. Both the bone and GLG data showed a general decrease in their δ13C (~2‰) and δ15N (~1‰) values between 1962 and 2007 indicating a change in trophic and prey source shift. To better understand the shift in prey source we analyzed strontium isotope composition (87Sr/86Sr) in GLGs for a sub-set of belugas and found a trend from marine towards a more freshwater signature. These results indicate a change in feeding ecology and a shift towards more freshwater influenced habitats both of which are consistent with survey data showing the summer range retracting into the upper reaches of Cook Inlet.

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