Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 7945
Title: Estimation of Salmonid Habitat Growth Potential Through Measurements of Invertebrate Food Abundance and Temperature
Author: Nicholas Weber, Nicholaas Bouwes, Chris E. Jordan
Publication Year: 2014
Journal: Canadian Journal of Fisheries and Aquatic Sciences
Keywords: streams,energetics,drift,growth,habitat

Criteria used to characterize lotic salmonid habitat suitability are often based on correlations between physical habitat characteristics and salmonid abundance. Focusing on physical habitat features ignores other habitat components such as an adequate food supply that limit the amount of energy available for growth and survival. We tested the degree food availability and temperature influence lotic salmonid consumption and growth rates, and outline an approach for assessing habitat quality based on measurements of these features. We collected benthic and drifting invertebrate abundances, stream temperatures, and juvenile steelhead/rainbow trout (Onchorhynchus mykiss gairdneri) summer growth rates among 9 stream segments in central Oregon. Stream temperatures and growth rates were used in bioenergetics model simulations to estimate O. mykiss consumption rates. The variation in O.mykiss consumption rates was explained by measurements of total drift biomass along a type II predator response curve (R2=0.71). This simplified foraging relationship between food abundance and consumption is then used to estimate the consumption component of the bioenergetics model to allow estimation of salmonid growth potential. Validation of the growth potential model produced reasonably accurate estimates of fish growth rates at reaches within the study area, and precise but biased estimates in novel systems. While additional reach level habitat information may be required to make the model more generalizable, the assessment of invertebrate food availability offers a simple yet powerful approach for describing the growth potential of stream habitat.

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