Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8229
Title: Salmon consumption by Kodiak brown bears (Ursus arctos middendorffi) with ecosystem management implications
Author: M. B. Van Daele, C. T. Robbins, B. X. Semmens, E. J. Ward, L. J. Van Daele, W. B. Leacock
Publication Year: 2013
Journal: Canadian Journal of Zoology
Volume: 91
Issue: 3
Pages: 164-174
Keywords: stable isotope,salmon,Whale,bear,Alaska
Abstract:

 The ecological role of large predators in North America continues to spark heated public debate.  Although brown bears and the salmon they feed on have declined in many areas, the Kodiak archipelago is famous for large brown bears and abundant salmon.  Salmon have generally been managed for maximum sustained yield in a fisheries sense, but those levels may be well below what is necessary for maximum ecosystem productivity.  Consequently, we used stable isotopes and mercury accumulated in hair to estimate intake of salmon by Kodiak brown bears (Ursus arctos middendorffi Merriam, 1896).  Salmon intake increased from subadult males (592 ± 325 kg/bear/yr) to adult males (2788 ± 1929) and from subadult females (566 ± 360 kg/bear/yr) to adult females (1364 ± 1261).  Intake within each group increased 62 ± 23% as salmon escapement increased from ~1500 to ~14,000 kg/bear/yr.  The estimated population of 2300 subadult and adult bears consumed 3.77 ± 0.16 million kg of salmon annually, a mass equal to 6% of the combined escapement and commercial harvest.  Although bears consume a small portion of the total mass of adult salmon, perpetuation of dense populations of large bears requires ecosystem-based management of the meat resources and environments that produce such bears.