Fish in Reservoirs

Abstract

In all reservoirs the fish fauna is recruited from their riverine antecedents. The nature of the riverine environment, created by its unstable hydrological regime, favours the evolution of generalist species. Of these species, only a few are preadapted to lacustrine conditions. When riverine fish communities are trapped in a reservoir, most of the fish stay close to the shore, the mouth of tributaries and in shallows. The pelagic and deep waters are poorly utilized and the yield of fish is below the natural productivity of these water bodies, especially in the case of deep and large reservoirs. This occurs unless the dammed river contains fish species from families which are preadapted for lacustrine conditions. A positive correlation between the percentage of pelagic fish and the total yield of fish in reservoirs indicates that the pelagial represents a vacant habitat, only seldom invaded by riverine species. This situation probably applies to the deep water of reservoirs too, although sufficient data to demonstrate this are not available.

The hydraulic management of the Barra Bonita reservoir (SP, Brazil) as a factor influencing the temporal succession of its fish community

“…Regarding the events resulted from the aging process, Fernando and Holcik (1991) claim that the ichthyofauna of reservoirs, at the first instance, results from the riverine species pre-adapted to lacustrine conditions. Subsequently, a population depletion is noticed which affects mainly the large-sized fish, usually migratory, of long life, and with low reproductive potential (k-strategists) species.…”

“…Several studies deal with the effects of the impoundment on the ichthyofauna (Branco and Rocha, 1977;Castro and Arcifa, 1987;Fernando and Holcik, 1991;Woynarovich, 1991;Granado-Lorencio, 1991Agostinho et al, 1994;Agostinho, 1995;Agostinho et al, 1999;Craig, 2000;Larinier, 2000). Nevertheless, the studies dealing with community changes in time, related to the hydraulic management of the reservoir are rare.…”

A pesca no reservatório da hidrelétrica de Balbina (Amazonas, Brasil)

“…De acordo com Fernando & Holcik (1991), a ictiofauna que se desenvolve em reservatórios é constituída por espécies que já ocorriam originalmente no sistema hidrográfico. Ainda segundo estes autores, o número de espécies de peixes presentes num reservatório é invariavelmente menor que nos trechos do mesmo rio não submetidos a represamento, o que se dá por causa da redução do número de habitats, bem como pela incapacidade da maioria das espécies fluviais de se adaptar ao ambiente lacustre.…”

Les réseaux trophiques lacustres: structure, fonctionnement, interactions et variations spatio-temporelles

“…Par contre, la surpêche ou l'introduction d'espèces prédatri-ces ou exotiques (en provenance d'autres bassins hydrographiques) est une pratique courante. Ceci peut provoquer des déséquilibres écologiques dans tes réseaux trophiques suite à la disparition des espèces natives (FERNANDO, 1991) tout en augmentant les rendements halieutiques lorsqu'il s'agit de filtreurs omnivores tel que le tilapia (FERNANDO et HOLCIK, 1991). Des effets importants de cascades trophiques ont été observés par ZARET et PAINE (1973) (PAIVA étal., 1994;GODINHO et al, 1994).…”