Effect of predation by Sacramento squawfish (Ptychocheilus grandis) on habitat choice of California roach (Lavinia symmetricus) and rainbow trout (Oncorhynchus mykiss) in artificial streams

Canadian Journal of Fisheries and Aquatic Sciences
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Abstract

We studied the effects of predatory Sacramento squawfish (Ptychocheilus grandis) on habitat choice of juvenile California roach (Lavinia symmetricus), adult roach, and juvenile rainbow trout (Oncorhynchus mykiss) in artificial streams. In single-prey trials, the proportion of fish found in pool habitat declined in the presence of squawfish for juvenile roach (from 0.55 to 0.00), adult roach (from 0.88 to 0.13), and juvenile rainbow trout (0.70 to 0.15). The presence of squawfish did not affect the use of riffle and edge habitats. Of the fish found in shallow water, the proportion found in edge habitat declined from juvenile roach (0.95) to adult roach (0.80) to juvenile rainbow trout (0.23). We also conducted experiments designed to simulate invasion of an area by squawfish, in which adult roach and juvenile rainbow trout were tested together in the presence and absence of squawfish. The proportion of prey in pool habitat in the presence of squawfish was greater in the two-prey trials than in the single-prey trials for both adult roach (0.31 and 0.13, respectively) and juvenile rainbow trout (0.33 and 0.15, respectively). These results support field evidence that squawfish are an important force in determining the spatial structure of native stream fish assemblages.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Effect of predation by Sacramento squawfish (Ptychocheilus grandis) on habitat choice of California roach (Lavinia symmetricus) and rainbow trout (Oncorhynchus mykiss) in artificial streams
Series title Canadian Journal of Fisheries and Aquatic Sciences
DOI 10.1139/f95-758
Volume 52
Issue 8
Year Published 1995
Language English
Contributing office(s) California Water Science Center
Description 8 p.
First page 1639
Last page 1646
Country United States
State California