Cycles in adult steelhead length suggest interspecific competition in the North Pacific Ocean

Canadian Journal of Fisheries and Aquatic Sciences
By: , and 

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Abstract

Anadromous fishes rely on abundant prey in the ocean to grow large quickly, but prey limitation leads to interspecific competition. When species interactions are difficult to observe, growth can be studied to detect otherwise cryptic signals of competition. We describe a previously undocumented two-year cycle in the lengths of adult natural-origin steelhead (Oncorhynchus mykiss) returning to spawn in the Snake River Basin. Returning steelhead were 38 mm shorter on odd return years, not accounting for sex, stock, and years of ocean residence. The well-known cycle in abundance of Pink Salmon from eastern Kamchatka and North America had statistically significant negative effects on returning steelhead lengths that depended on sex and the number of years of ocean residence. These results suggest that competition for limited resources occurs well after initial ocean entry and that interactions during later stages of ocean residence can be influential. Interspecific competition has implications for future returns of steelhead from the ocean, especially as metabolic demands for steelhead increase as the ocean warms.

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Publication type Article
Publication Subtype Journal Article
Title Cycles in adult steelhead length suggest interspecific competition in the North Pacific Ocean
Series title Canadian Journal of Fisheries and Aquatic Sciences
DOI 10.1139/cjfas-2023-0374
Volume 81
Issue 12
Year Published 2024
Language English
Publisher Canadian Science Publishing
Contributing office(s) Coop Res Unit Seattle
Description 10 p.
First page 1666
Last page 1675
Country Russia, United States
Other Geospatial North Pacific Ocean
Additional publication details