Introdução de espécies de peixes por escapes acidentais de tanques de cultivo em rios da Bacia do Rio Paraná, Brasil

Abstract

ABSTRACT. Fish species introduction by accidental escape from aquaculture in the high Paraná River Basin. Species composition and abundance of fishes that escaped from aquaculture facilities during catastrophic flooding in the Paranapanema and Tibagi rivers, in January, 1997 was estimated. ln ali, 1,292,000 adult individuais belonging to II species and I hybrid, were introduced into these rivers; only one species was native . The disaster is attributed to the illegal occupation ofthe river banks, and the non observance of standard measures designed to avoid escapement. KEY WORDS . Species introduction, Tibagi river, Paranapanema, river A piscicultura é considerada o principal meio de dispersão de espectes exóticas em novos ambientes (WELCOMME 1988; AGOSTINHO & JULIO 1996). Os escapes com a água efluente, o esvaziamento dos tanques durante o manejo e, principalmente, o rompimento ou transbordamento desses em razão de picos de cheias não previstos durante a construção, são as principais vias de introdução de espécies exóticas pelas atividades de cultivo. Nesse contexto contribui a prática comum da piscicultura brasileira em estabelecer seus cultivos nas proximidades dos rios, dentro da área de preservação permanente, e, portanto, sujeita a alagamentos nos anos de grandes cheias. Uma forma recente de comercialização e lazer, os chamados "pesque e pague", embora ainda não avaliados, devem se constituir em importantes riscos adicionais de disseminação de espécies exóticas (peixes e doenças) .Visando dimensionar os escapes de peixes dos sistemas de cultivo para os cursos de água da bacia do rio Paranapanema em anos de grandes cheias, foi realizado um levantamento em 38 propriedades rurais privadas com atividade aquícola, sendo a grande maioria propriedades de produção para a revenda (31) e poucos pesque-pague (7) (sub-bacias do médio e baixo Tibagi, baixo Cinzas e parte do Paranapanema, figura I), em áreas atingidas pelas cheias de janeiro e fevereiro de 1997.

A massive invasion of fish species after eliminating a natural barrier in the upper rio Paraná basin

“…Leporinus macrocephalus, an anostomid from the lower Paraná ecoregion, was intensively stocked (Agostinho et al, 2007b), escaped from aquaculture ponds (Orsi & Agostinho, 1999), ascended the Itaipu fish passage (Makrakis et al, 2007) and is currently abundant in the upper rio Paraná. Although this species could have dispersed due to the elimination of the Sete Quedas barrier, it was not included because this obstacle suppression probably was not the main reason for its introduction.…”

Reproduction of a South American population of pumpkinseed sunfish Lepomis gibbosus (Linnaeus) (Osteichthyes, Centrarchidae): a comparison with the European and North American populations

“…On a global level, the United States and Brazil are the countries with the highest number of non-native fishes (WELCOMME 1988, FULLER et al 1999) and the state of Minas Gerais leads the ranking with over 40 species, followed by the states of northeast (N = 39), state of Rio de Janeiro (N = 37), Federal District (N = 15) state of Paraná (N = 13), states of Santa Catarina and Rio Grande do Sul (N = 10) (GURGEL & OLIVEIRA 1987, ORSI & AGOSTINHO 1999, RIBEIRO et al 2000, POLI et al 2000, BIZERRIL & LIMA 2001, MAGALHÃES et al 2002.…”

First records of introduced carps (Teleostei, Cyprinidae) in the natural habitats of Mirim and Patos Lagoon estuary, Rio Grande do Sul, Brazil

“…GARCIA et al (2003) showed that freshwater fishes inhabiting the northern reaches of Patos Lagoon and its tributaries are carried into the lower reaches of the lagoon, and even the adjacent marine coastal area, during periods of elevated rainfall and high freshwater discharge. Several studies elsewhere have documented the escape of introduced carps from aquaculture into natural habitats (see NAYLOR et al 2001 for further references), including some cases in southeastern Brazil (AGOSTINHO & JULIO 1996, ORSI & AGOSTINHO 1999. Silver and bighead carps, which have already established as reproducing populations elsewhere, have been associated with the following threats to native fish communities: (a) they are powerful filter-feeders and they have the potential to out-compete native filter-feeder fishes (b) they consume a broad food spectrum, and can reduce zooplankton abundance, (c) they are fast growing and can reproduce quickly (XIE & CHEN 2001).…”