Factors controlling the abundance of rainbow trout in the Colorado River in Grand Canyon in a reach utilized by endangered humpback chub

Canadian Journal of Fisheries and Aquatic Sciences
By: , and 

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Abstract

We estimated the abundance, survival, movement, and recruitment of non-native rainbow trout in the Colorado River in Grand Canyon to determine what controls their abundance near the Little Colorado River (LCR) confluence where endangered humpback chub rear. Over a 3-year period, we tagged more than 70,000 trout and recovered over 8,200 tagged fish. Trout density was highest (10,000-25,000 fish/km) in the reach closest to Glen Canyon Dam where the majority of trout recruitment occurs, and was 30-50-fold lower (200-800 fish/km) in reaches near the LCR confluence ~100 km downstream. The extent of rainbow trout movement was limited with less than 1% of recaptures making movements greater than 20 km. However, due to high trout densities in upstream source areas, this small dispersal rate was sufficient to explain the 3-fold increase in the relatively small population near the LCR. Reducing dispersal rates of trout from upstream sources is the most feasible solution to maintain low densities near the LCR to minimize negative effects of competition and predation on humpback chub.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Factors controlling the abundance of rainbow trout in the Colorado River in Grand Canyon in a reach utilized by endangered humpback chub
Series title Canadian Journal of Fisheries and Aquatic Sciences
DOI 10.1139/cjfas-2015-0101
Volume 73
Issue 1
Year Published 2015
Language English
Publisher NRC Research Press
Contributing office(s) Southwest Biological Science Center
Description 20 p.
First page 105
Last page 124
Time Range Start 2012-04-01
Time Range End 2014-09-30
Country United States
State Arizona
Other Geospatial Colorado River, Grand Canyon
Online Only (Y/N) N
Additional Online Files (Y/N) N