Avaliação do caráter multiuso do Canal da Piracema para a transposição de peixes Neotropicais no rio Paraná, Brasil .

Abstract

The Canal da Piracema is the longest fish passage in the world and the solely of its kind in South America. It was constructed aiming to favor the gene flow of the Paraná River ichthyofauna and to promote outdoors activities, such as canoeing and rafting, in some components of the Canal. The studies already conducted in the Canal evaluated species richness and the ascent efficiency of migratory species using distinct methodologies (surveys and radiotelemetry). The purpose of this study was to evaluate the possible multiple uses of the Canal. Specifically, it was evaluated the effect of canoeing on fish movements and the factors that may restrict the ascent efficiency of migratory species. The influence of canoeing was studied based on samplings of fish conducted in the sector of the Canal named Canal de Águas Bravas (CAAB), comparing samples gathered in days with and without canoeing. Models for every possible influence scenario were proposed and adjusted to identify the best fit. Differences observed in the relative abundances of fish in CAAB showed the possible dissuasive effect of canoeing. The ascent of migratory fish was evaluated using the technology of radio frequency identification (RFID) and passive electronic tags (PIT). Significant differences were obtained in the time (in days) of ascent for individuals tagged and released downstream the sector Canal de Deságue do rio Bela Vista (CABV; considered the bottleneck of the Canal) from those tagged and released upstream this sector. The results indicated that the time of permanence in the Canal is high, which may compromise reproductive strategies. In addition, fish movements of tagged fish (mainly Characiformes) occurred during the day. Thus, PIT tag contributed to obtain more detailed information on the effect of CABV in the movements of fish in the Canal.