No abstract

The Brazilian Government has been promoting studies on the zoning and demarcation of aquaculture parks dedicated to the production of fish in net-cages in the large public reservoirs of the country. The methodology employed for the zoning of these aquaculture parks consists of the execution in three consecutive stages of multidisciplinary evaluations for their social, environmental and economical characterization (global, regional and local). The purpose of the studies involves the generation of thematic maps and scenarios of environmental models that facilitate the process of understanding the regional peculiarities and taking the decisions to identify the most appropriate areas for the installation of the aquaculture parks. The application of this instrument for zoning the reservoirs will assist a more effective planning of investments and efforts, both by the government and by private initiative, in the aquaculture activity. With the implantation of aquaculture parks along the lines of an ecosystemic aquaculture, Brazil has the potential to become one of the largest producers of fish in net-cages in the world.

This study presents results from several expeditions in 1985, 1991-1995 and 2003 to the Medium Paraná River in the section that begins below the Itaipu Dam and ends at the trinational border of Brazil, Argentina and Paraguay, in the lotic and lentic zones of the reservoir of the Hydroelectric Power Station of “Itaipu Binacional” (localities Foz do Iguaçu, Santa Helena and Guaira). Ninety-eight species of freshwater fishes belonging to 22 families were examined for helminths. A host-parasite list based on Acanthocephala, Cestoda, Digenea, Monogenea and Nematoda collected from the region in question is provided. New host records are presented for Digenea and Nematoda. The Monogenea and Acanthocephala are being studied and will be published in a later paper, but are referred in the host-parasite list, in order to demonstrate the parasitism in the fishes of the reservoir. The results are compared with those presented by other authors from the Upper Paraná River.

A study was carried out from 23 October to 19 November 1992 to determine the ability of fish to ascend the fish ladder at the ITAIPU dam, to identify the species attracted and to evaluate possible fish selection. The results show that some species of fish can ascend the ladder during the migratory period; the dam is non-selective with respect to species, but selective with respect to fish size as a result of the presence of reduced openings. The ladder was ascended by both scaly species from surface waters (agile movers) and by deep water species which were characterized by slow movements. An average of 2892 fish ascended the ladder each day. The weight and length of fish recorded ranged from 336.0 to 3676.0 g and from 30.2 to 71.3 cm, respectively. The largest group of migrating fish was the curimba (Prochilodus scrofa). The high ratio of 72% of fish in the gonadal development stage, classified as 'maturing', indicates that the species caught in the ladder were migrating for reproduction purposes.

No abstract