Predation on native sculpin by exotic brown trout exceeds that by native cutthroat trout within a mountain watershed (Logan, UT, USA)

Ecology of Freshwater Fish
By: , and 

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Abstract

We explored potential negative effects of exotic brown trout (Salmo trutta) on native sculpin (Cottus sp.) on the Logan River, Utah, USA by (i) examining factors most strongly correlated with sculpin abundance (e.g., abiotic conditions or piscivory?), (ii) contrasting the extent of brown trout predation on sculpin with that by native cutthroat trout (Oncorhynchus clarkii utah) and (iii) estimating the number of sculpin consumed by brown trout along an elevational gradient using bioenergetics. Abundance of sculpin across reaches showed a strong (r ≥ 0.40) and significant (P < 0.05) correlation with physical variables describing width (positive) and gradient (negative), but not with abundance of piscivorous brown trout or cutthroat trout. In mainstem reaches containing sculpin, we found fish in 0% of age‐1, 10% of age‐2 and 33% of age‐3 and older brown trout diets. Approximately 81% of fish consumed by brown trout were sculpin. Despite a similar length–gape relationship for native cutthroat trout, we found only two fish (one sculpin and one unknown) in the diets of native cutthroat trout similar in size to age‐3 brown trout. Based on bioenergetics, we estimate that an average large (> 260 mm) brown trout consumes as many as 34 sculpin per year. Nevertheless, results suggest that sculpin abundance in this system is controlled by abiotic factors and not brown trout predation. Additional research is needed to better understand how piscivory influences brown trout invasion success, including in‐stream experiments exploring trophic dynamics and interactions between brown trout and native prey under different environmental conditions.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Predation on native sculpin by exotic brown trout exceeds that by native cutthroat trout within a mountain watershed (Logan, UT, USA)
Series title Ecology of Freshwater Fish
DOI 10.1111/eff.12134
Volume 24
Issue 1
Year Published 2015
Language English
Publisher Wiley
Contributing office(s) Coop Res Unit Seattle
Description 15 p.
First page 133
Last page 147
Country United States
State Utah
Other Geospatial Logan River
Online Only (Y/N) N
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