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

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,...

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Bibliographic Details
Published inCanadian journal of fisheries and aquatic sciences Vol. 80; no. 11; pp. 1723 - 1736
Main Authors Freeman, Mary C, Albanese, Brett, Bumpers, Phillip M, Hagler, Megan M, Nagy, Andrew J, Freeman, Byron J, Wenger, Seth J
Format Journal Article
LanguageEnglish
Published Ottawa NRC Research Press 01.11.2023
Canadian Science Publishing NRC Research Press
Subjects
Body size
Dams
Downstream
Environmental aspects
Fish
Fishes, Fresh-water
Hydroelectric dams
Hydroelectric power
Hydroelectric power plants
Life span
Rivers
Species richness
Streams
Surveys
Tributaries
Water circulation
Wildlife conservation
United States
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Summary: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.
ISSN:0706-652X
1205-7533
DOI:10.1139/cjfas-2022-0297