Persistence of native riverine fishes downstream from two hydropower dams with contrasting operations

Canadian Journal of Fisheries and Aquatic Sciences
By: , and 

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Abstract

Identifying hydropower dam operations that lessen detrimental effects on downstream fauna could inform conservation strategies for native fishes. We compared occurrence of native fishes in 20 shoal habitats downstream from two differently operated hydropower dams in the Coosa River system, Georgia, USA. Species richness averaged 7 and 11, respectively, in surveys downstream from (1) a hydropeaking dam and (2) a dam with a re-regulation structure that stabilized downstream flows. In contrast, surveys in two nearby reference communities averaged 19 and 24 species. Species persisting downstream from the dams tended toward water-column orientation, larger body size, longer life-span, and greater prevalence in tributary stream collections, compared with missing or rarely captured species. We observed no evidence of recovery toward reference conditions when operations were paused for 28 months at the hydropeaking dam. Our observations suggest that (1) strongly contrasting dam operations can result in similar alterations to native fish assemblages, potentially reflecting effects of thermal alteration by hypolimnetic water release, and (2) periodic dispersal from tributary streams may enhance fish persistence in flow-altered rivers.
Publication type Article
Publication Subtype Journal Article
Title Persistence of native riverine fishes downstream from two hydropower dams with contrasting operations
Series title Canadian Journal of Fisheries and Aquatic Sciences
DOI 10.1139/cjfas-2022-0297
Volume 80
Issue 11
Year Published 2023
Language English
Publisher Canadian Science Publishing
Contributing office(s) Patuxent Wildlife Research Center, Eastern Ecological Science Center
Description 14 p.
First page 1723
Last page 1736
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