Predation of juvenile salmonids by smallmouth bass and northern squawfish in the Columbia River near Richland, Washington

North American Journal of Fisheries Management
By: , and 

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Abstract

The importance of juvenile salmonids in the diet of smallmouth bass Micropterus dolomieu and northern squawfish Ptychocheilus oregonensis was examined at a 6-km stretch of the Columbia River. Piscivorous fish were sampled with electrofishing gear on 4 d (May 2–3 and June 20–21, 1990) during emigration of juvenile anadromous salmonids. Sixty-two smallmouth bass and 69 northern squawfish were collected for diet analysis. Juvenile salmonids made up 59% of smallmouth bass diet by weight and were present in 65% of the stomachs of smallmouth bass. By a meal turnover method, smallmouth bass were estimated to consume from 1.4 (May 2–3) to 1.0 (June 20–21) salmonids per predator daily. Crayfish were the dominant prey item (41.4% by weight) of northern squawfish, but juvenile salmonids (28.8%) were also important. Northern squawfish consumed from 0.55 (May 2–3) to 0.34 (June 20–21) salmonids per predator daily. Smallmouth bass and northern squawfish consumed mostly subyearling Chinook salmon Oncorhynchus tshawytscha, which may have been wild Chinook salmon that emigrated downstream from the Hanford reach. Predation rates on salmonids by smallmouth bass are apparently high during spring and early summer because subyearling Chinook salmon are abundant and of suitable forage size and their habitat overlaps with that of smallmouth bass.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Predation of juvenile salmonids by smallmouth bass and northern squawfish in the Columbia River near Richland, Washington
Series title North American Journal of Fisheries Management
Volume 13
Issue 4
Year Published 1993
Language English
Publisher Taylor & Francis
Contributing office(s) Western Fisheries Research Center
Description 8 p.
First page 831
Last page 838
Country United States
State Oregon
Other Geospatial Columbia River