Estimating recruitment dynamics and movement of rainbow trout (Oncorhynchus mykiss) in the Colorado River in Grand Canyon using an integrated assessment model

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 69; no. 11; pp. 1827 - 1849
• Main Authors: KORMAN, Josh, MARTELL, Steven J. D, WALTERS, Carl J, MAKINSTER, Andrew S, COGGINS, Lewis G, YARD, Michael D, PERSONS, William R
• Format: Journal Article
• Language: English
• Published: Ottawa, ON NRC Research Press 01.11.2012; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Agnatha. Pisces; Animal and plant ecology; Animal migration; Animal, plant and microbial ecology; Animals; Approximation; Aquatic ecology; Behavior; Biological and medical sciences; Canyons; Dams; Demecology; Distribution; Emigration; Environmental aspects; Fishes; Fresh water ecosystems; Freshwater; Fundamental and applied biological sciences. Psychology; Migration; Native species; Oncorhynchus mykiss; Rivers; Salmon; Sand bars; Stock assessment (Wildlife management); Streamflow; Synecology; Trout; Vertebrata; United States; North America; Arizona; America; Glen Canyon Dam; United States > US; Colorado River; USA, Arizona, Grand Canyon, Colorado R; Evaluation; Introduced species; Grand Canyon; Oncorhynchus mykiss; Freshwater environment; Vertebrata; Pisces; Population recruitment; Stream; Population dynamics; Models; Native species; Comparative study
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/f2012-097

We used an integrated assessment model to examine effects of flow from Glen Canyon Dam, Arizona, USA, on recruitment of nonnative rainbow trout ( Oncorhynchus mykiss ) in the Colorado River and to estimate downstream migration from Glen Canyon to Marble Canyon, a reach used by endangered native fish. Over a 20-year period, recruitment of rainbow trout in Glen Canyon increased with the annual flow volume and when hourly flow variation was reduced and after two of three controlled floods. The model predicted that approximately 16 000 trout·year –1 emigrated to Marble Canyon and that the majority of trout in this reach originate from Glen Canyon. For most models that were examined, over 70% of the variation in emigration rates was explained by variation in recruitment in Glen Canyon, suggesting that flow from the dam controls in large part the extent of potential negative interactions between rainbow trout and native fish. Controlled floods and steadier flows, which were originally aimed at partially restoring conditions before the dam (greater native fish abundance and larger sand bars), appear to have been more beneficial to nonnative rainbow trout than to native fish.