reference : Warming ocean conditions relate to increased trophic requirements of threatened and endangered salmon

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Bibliographic fields
reftype Journal Article
Abstract The trophic habits, size and condition of yearling Chinook salmon (Oncorhynchus tshawytscha) caught early in their marine residence were examined during 19 survey years (1981–1985; 1998–2011). Juvenile salmon consumed distinct highly piscivorous diets in cold and warm ocean regimes with major differences between ocean regimes driven by changes in consumption of juvenile rockfishes, followed by several other fish prey, adult euphausiids and decapod larvae. Notable, Chinook salmon consumed 30% more food in the warm versus cold ocean regime in both May and June. Additionally, there were about 30% fewer empty stomachs in the warm ocean regime in May, and 10% fewer in warm June periods. The total prey energy density consumed during the warmer ocean regime was also significantly higher than in cold. Chinook salmon had lower condition factor and were smaller in fork length during the warm ocean regime, and were longer and heavier for their size during the cold ocean regime. The significant increase in foraging during the warm ocean regime occurred concurrently with lower available prey biomass. Adult return rates of juvenile Chinook salmon that entered the ocean during a warm ocean regime were lower. Notably, our long term data set contradicts the long held assertion that juvenile salmon eat less in a warm ocean regime when low growth and survival is observed, and when available prey are reduced. Comparing diet changes between decades under variable ocean conditions may assist us in understanding the effects of projected warming ocean regimes on juvenile Chinook salmon and their survival in the ocean environment. Bioenergetically, the salmon appear to require more food resources during warm ocean regimes.
Author Daly, Elizabeth A.; Brodeur, Richard D.
DOI 10.1371/journal.pone.0144066
Issue 12
Journal PLOS ONE
Pages e0144066
Publisher Public Library of Science
Title Warming ocean conditions relate to increased trophic requirements of threatened and endangered salmon
Volume 10
Year 2015
Bibliographic identifiers
_record_number 24674
_uuid 7777eee9-2f8e-45d8-bf6d-ec33a9c8bf43