The fish fauna in the fish passage at the Ourinhos Dam, Paranapanema River

Abstract

The composition and abundance of the fish assemblage were evaluated in the fish ladder of Ourinhos Dam, the newest dam (closed in 2005) in the cascade of dams constructed on the Paranapanema River. Samplings were carried out three times on a diel cycle, in three sampling periods, two in the warm season and one in the cold season of 2008 -2009. The ladder was closed and emptied and the entire fish assemblage was sampled and identified. Most individuals were released alive downstream of the dam. The assemblage found in the ladder was compared with the fish fauna sampled in the reservoir and in downstream sites, in the same period. Twenty seven species and a total of 4682 individuals were caught in the ladder. Pimelodus maculatus was the only migratory species, which was caught in low number in the ladder (0.04% of the total captured), where small sedentary species predominated. The most abundant species were the non-migratory Apareiodon affinis, Bryconamericus stramineus, Astyanax fasciatus and Parodon nasus. Individuals observed in the ladder's window were moving up-and down the passage. The fish ladder is a microhabitat inhabited by an abundant association of benthic organisms that is probably used as a food resource for the fish assemblage in the ladder. The similarity between the fish fauna in the ladder and that of the Ourinhos Reservoir was low (26%). The species richness of migrants in the stretch between the uspstream reservoir (Chavantes) and the downstream one (Salto Grande), before the Ourinhos dam closure (23 species) was reduced to 16 and 12 species in Salto Grande and Ourinhos reservoirs, respectively, after the dam closure, and to a single species in the ladder.A composição e abundância da ictiofauna da escada de peixes da barragem de Ourinhos, a mais nova hidrelétrica (fechada em 2005) na sequência de barragens construídas no rio Paranapanema, foram avaliadas três vezes em um ciclo diário, em três períodos de coleta, dois no verão e um no inverno de [2008][2009]. A escada foi fechada e esvaziada e os peixes coletados e identificados, antes da devolução da maior parte deles a jusante. A ictiofauna da escada foi comparada à do reservatório de Ourinhos, coletada na mesma época. Vinte e sete espécies e 4862 indivíduos foram coletados na escada. Pimelodus maculatus foi a única espécie migradora coletada, mas em número baixo na escada, onde predominaram espécies sedentárias pequenas. As espécies mais abundantes foram as sedentárias Apareiodon affinis, Bryconamericus stramineus, Astyanax fasciatus e Parodon nasus. Observações feitas na janela da escada revelaram que os peixes realizavam movimentos ascendentes e descendentes. A escada de peixes é um microhabitat habitado por uma abundante associação de organismos bentônicos que é provavelmente usada como recurso alimentar pela ictiofauna na escada. A similaridade entre a ictiofauna no reservatório de Ourinhos e na escada é baixa (26%). A riqueza de espécies migradoras no trecho entre os reservatórios a montante (Chavantes) e a jusante (Salto Grande), ante...

Fish fauna from the Paranapanema River basin, Brazil

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Fish diversity in the cascade of reservoirs along the Paranapanema River, southeast Brazil

“…1). Fish passages (ladders) were installed in five dams, namely Canoas I, Canoas II, Ourinhos, Paranapanema and Piraju (Arcifa, Esguícero, 2012;Britto, Carvalho, 2013). Fig.…”

Ichthyofauna of streams of the Lower Paranapanema River basin, state of Paraná, Brazil

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