Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 7511
Title: Documentation of unusual fall spawning by coastal cutthroat trout in the Elwha River system, Washington
Author: John R. McMillan, Mike McHenry, G. R. Pess, Raymond Moses, T. P. Quinn
Publication Year: 2014
Journal: Transactions of the American Fisheries Society
Volume: 143
Issue: 6
Pages: 1605-1611
Keywords: life history,cutthroat trout,dam removal,streamflow,coho salmon,ecological interactions,

The timing of breeding is a key trait, reflecting selective forces acting on the adults and offspring in the population, contributing to reproductive isolation, and affecting the populations success during rapid environmental change. Salmon and trout populations vary greatly in the peak and range of breeding times, and timing is a defining trait for salmonid populations. This study reports the occurrence and details of spawning by coastal cutthroat trout, Oncorhynchus clarki clarki, in Indian Creek in the Elwha River, Washington State, in October and November, unusually early in the season for this characteristically spring-spawning species. This timing is much earlier than conspecifics elsewhere in the river system and the region. We hypothesize that the streams low gradient and lake-dampened hydrologic regime reduce the depth of fall gravel scours, and thus have permitted the evolution of such early breeding date by these small-bodied (ca. 20 - 35 cm) fish. The exclusion of sympatric fall-spawning coho salmon, O. kisutch, for the past century from the habitat by Elwha Dam may have contributed to this adaptation as well, and the re-colonization by coho salmon may strongly affect the cutthroat trout through redd disturbance by the larger and later-spawning salmon.

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Theme: Habitats to Support Sustainable Fisheries and Recovered Populations
Foci: Characterize relationships between habitat and ecosystem processes, climate variation, and the viability of organisms.
Develop effective and efficient habitat restoration and conservation techniques.