Species and stock identification of prey consumed by endangered southern resident killer whales in their summer range

Endangered Species Research

Gregory S. Schorr¹  Brian Gisborne¹  Kelley Balcomb-Bartok¹  John G. Sneva¹  M. Bradley Hanson¹  John R. Candy¹  John K. B. Ford¹  Jennifer Hempelmann-Halos¹  Donald M. Van Doornik¹  Katherine L. Ayres¹  Kenneth C. Balcomb¹  Candice K. Emmons¹  Samuel K. Wasser¹  Robin W. Baird¹  Michael J. Ford¹ 

关键词: Resident killer whales;    Prey selection;    Chinook salmon;    Genetic stock identification;   

DOI  :  10.3354/esr00263

学科分类：动物科学

来源: Inter-Research

【 摘 要 】

ABSTRACT: Recovery plans for endangered southern resident killer whales Orcinus orca have identified reduced prey availability as a risk to the population. In order to better assess this risk, we studied prey selection from 2004 to 2008 in 2 regions of the whales’ summer range: San Juan Islands, Washington and the western Strait of Juan de Fuca, British Columbia. Following the whales in a small boat, we collected fish scales and tissue remains from predation events, and feces, using a fine mesh net. Visual fish scale analysis and molecular genetic methods were used to identify the species consumed. Chinook salmon, a relatively rare species, was by far the most frequent prey item, confirming previous studies. For Chinook salmon prey, we used genetic identification methods to estimate the spawning region of origin. Of the Chinook salmon sampled, 80 to 90% were inferred to have originated from the Fraser River, and only 6 to 14% were inferred to have originated from Puget Sound area rivers. Within the Fraser River, the Upper Fraser, Middle Fraser, South Thompson River and Lower Fraser stocks were inferred to currently be sequentially important sources of Chinook salmon prey through the summer. This information will be of significant value in guiding management actions to recover the southern resident killer whale population.

【 授权许可】

Unknown