The utilization of a Pacific salmon Oncorhynchus nerka subsidy by three populations of charr Salvelinus spp.
Article first published online: 18 AUG 2010
© 2010 The Authors. Journal compilation © 2010 The Fisheries Society of the British Isles
Journal of Fish Biology
Volume 77, Issue 4, pages 1006–1023, September 2010
How to Cite
Denton, K. P., Rich, H. B., Moore, J. W. and Quinn, T. P. (2010), The utilization of a Pacific salmon Oncorhynchus nerka subsidy by three populations of charr Salvelinus spp. Journal of Fish Biology, 77: 1006–1023. doi: 10.1111/j.1095-8649.2010.02746.x
- Issue published online: 14 SEP 2010
- Article first published online: 18 AUG 2010
- (Received 10 March 2010, Accepted 25 June 2010)
- Iliamna Lake;
- length at age;
- stable isotopes
The LF-at-age trajectories differentiated two populations of Dolly Varden charr Salvelinus malma and a population of Arctic charr Salvelinus alpinus from the eastern end of Iliamna Lake, Alaska. Salvelinus malma from the Pedro Bay ponds were the smallest for a given age, followed by Salvelinus alpinus from the lake, and S. malma from the Iliamna River were much larger. The utilization of a large sockeye salmon Oncorhynchus nerka subsidy by the three Salvelinus spp. populations was then investigated by comparing diet data and mixing model (MixSIR) outputs based on carbon and nitrogen stable isotopes. Stomach contents indicated that both S. malma populations fed on O. nerka products, especially eggs and larval Diptera that had scavenged O. nerka carcasses, whereas S. alpinus fed on a variety of prey items such as three-spined sticklebacks Gasterosteus aculeatus and snails. Stable-isotope analysis corroborated the diet data; the two S. malma populations incorporated more O. nerka-derived nutrients into their tissues than did S. alpinus from the lake, although all populations showed substantial utilization of O. nerka-derived resources. Salvelinus alpinus also seemed to be much more omnivorous, as shown by stable-isotope mixing models, than the S. malma populations. The dramatic differences in growth rate between the two S. malma populations, despite similar trophic patterns, indicate that other important genetic or environmental factors affect their life history, including proximate temperature controls and ultimate predation pressures.