The Canal da Piracema at Itaipu Dam as a fish pass system

Abstract

The Canal da Piracema is the longest (nearly 10 km) fish pass system in the world. The construction of this fish pass was somehow controversial, because it connected two distinct ichthyofaunistic provinces. This study evaluated the ichthyofauna present in the Canal da Piracema and the abundance and distribution of long-distance migratory fish species along this fish pass system (evaluated possible selectivity). The Canal da Piracema was shown to be difficult to sample because of its environmental heterogeneity: artificial ponds, ladders and nature-like fish pass. To solve this problem, we used several fishing gears, adequate for the several biotopes present (unstructured and structured littoral were sampled with seining nets and electrofishing; lentic were sampled with gillnets and longlines (deeper areas); and rapid water areas were sampled with cast nets). The ichthyofauna of the Canal da Piracema followed the pattern for South America and the Paraná River, with a predominance of Characiformes and Siluriformes. The most representative families were Characidae, Anostomidae, Pimelodidae and Loricariidae. We captured 116 species (17 were long-distance migratory) during the period studied. Small-sized species were predominant in unstructured and structured littoral areas, especially Bryconamericus exodon and Apareiodon affinis. The most abundant species was Hypostomus spp. in lentic areas, followed by Iheringichthys labrosus. Hoplias aff. malabaricus predominated in deeper lentic areas. Long-distance migratory species were abundant in rapid waters; they were Prochilodus lineatus and Leporinus elongatus. The sharp reduction in the number of species, including migratory ones, is an indication that the Canal da Piracema is selecting the species that ascend it. Therefore, the search for information on the efficiency of the various fish passes present in the Canal da Piracema is fundamental, to facilitate upward movements of fish. If this is reached, this polemic fish pass has the potential to contribute to the conservation of fish stocks in Itaipu Reservoir and upstream stretches, because of the presence of spawning and development (nurseries) areas for migratory species.O Canal da Piracema é considerado o maior sistema de transposição para peixes no mundo, com 10 km de extensão. A sua construção foi controversa, pois viabilizou a conexão entre duas províncias ictiofaunísticas distintas. Este trabalho buscou avaliar a ictiofauna presente no Canal da Piracema, a abundância e distribuição das espécies migradoras de longa distância ao longo deste sistema de transposição (indicação de seletividade). O Canal da Piracema mostrou-se difícil de ser amostrado, devido a sua elevada heterogeneidade ambiental: lagos artificiais, escadas e canais semi-naturais, sendo utilizados diversos aparelhos de pesca, adequados aos diversos biótopos (litoral não estruturado e estruturado, amostrados com redes de arrasto e pesca elétrica; lêntico, amostrado com redes de espera e espinhel (mais profundo); e águas rápidas, amostradas com tarrafa...

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

“…Bryconamericus exodon, for example, was the most abundant species in the Canal de Piracema. At least ten other species from the lower Paraná, but absent upstream, were captured in surveys conducted in the 10 kilometer long channel (Makrakis et al, 2007).…”

“…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.…”

Morphological differentiation among migratory fish species from the Paraná River basin

“…To analyze the most appropriate morphological patterns for the species' movement related to swimming capacity, morphometric measurements were taken in nine long-distance migratory fish species (Agostinho et al 2003, Suzuki et al 2004, Makrakis et al 2007), totaling 177 individuals (Table 1).…”

“…Thus, species from group III may have a higher swimming performance in relation to other species studied, as observed by the values of fineness ratio. Studies conducted in the Piracema Canal by Makrakis et al (2007) demonstrated that the species Leporinus elongatus, L. obtusidens, P. lineatus and Salminus brasiliensis, all species considered good swimmers, pass easier through the Piracema Canal. This feature may also be attributed to the morphological characteristics of these species, because they have been the most hydrodynamic body providing greater performance swimming.…”

“…The Piracema Canal is a complex 10-km fish pass system that climbs 120 m to connect the Paraná River to the Itaipu Reservoir along the Brazil-Paraguay border (Makrakis et al 2011). The canal includes a large section of a natural streambed as well as several fish ladders, artificial lakes and semi-natural channels, and the mean water velocity range from 0.9 to 3.0 m/s (for details see Makrakis et al 2007).…”