Influence of seasonal, diel, lunar, and other environmental factors on upstream fish passage in the Igarapava Fish Ladder, Brazil |
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| Authors: | P M Bizzotto A L Godinho V Vono B Kynard H P Godinho |
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| Institution: | Graduate Program on Vertebrate Zoology, Pontifical Catholic University of Minas Gerais, Belo Horizonte, MG, Brazil;, Fish Passage Center, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil;, U.S. Geological Survey, Leetown Science Center, S.O. Conte Anadromous Fish Research Center, Turners Falls, MA, USA |
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| Abstract: | Abstract – Upstream fish passage was evaluated during 12 months in the vertical-slot Igarapava Fish Ladder constructed around Igarapava Dam, in the heavily dammed Grande River, Southeast Brazil. A video monitoring system was used to observe 61,621 fish that passed the ladder, of which 93.5% were identified to 15 taxa. Among the migratory species, the most abundant were Pimelodus maculatus (33.6% of all fish), Leporinus octofasciatus (31.4%), Leporinus friderici (4.5%), and Prochilodus lineatus (3.1%). Seven taxa were classified as nonmigratory, and of these taxa, the small Bryconamericus stramineus was the most abundant (12.7%) of all fishes. Passage of the 'nonmigratory' taxa upstream in the ladder shows they are migratory in this system and have a strong behavioural drive to move to upstream habitat. Passage of most taxa had a strong seasonal pattern. While some species passed primarily during the day, others showed a distinct nocturnal pattern. Lunar phase and water temperature also strongly affected passage of some taxa. Rainfall and dam discharge had a small or null influence on most taxa; perhaps due to the fairly small catchment area of the reservoir and the highly regulated discharge at Igarapava Dam. |
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| Keywords: | vertical-slot fish ladder Neotropical fish passage fish migration Grande River Paraná River basin |
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