Abstract:
The effectiveness of fishways should consider the senses of fish movements, both downstream and upstream, if we really want to have them as a tool to minimize the dam impacts. In this study we evaluated the effectiveness of the fishway of the Hydropower Plant “Engenheiro Sergio Motta” (Porto Primavera dam), Upper Paraná River, southeastern Brazil, during 627 days between December, 2012 and August, 2014. We tagged 995 fish with PITtags 23mm, distributed in 628 Prochilodus lineatus and 367 Leporinus obtusidens. The fish were released both downstream (416 P. lineatus and 58 L. obtusidens) and upstream of the dam (212 P. lineatus and 309 L. obtusidens). A total of 145 (34.8%) P. lineatus tagged downstream concluded the passage and 25 (17.2%) of those passed back. The average time of the upstream movement were 201.4 days, with a minimum of 01h 07min and a maximum of 448 days. Of the 58 L. obtusidens released in downstream, 19 individuals (32.8%) ascent the fishway and of these there were no subsequent downstream movements. From 212 P. lineatus tagged upstream, 34 (16%) descent the fishway, with a mean of 148.8 days, minimum of 1hr 54min and maximum of 421.5 days. As for the 309 L. obtusidens released upstream, 21 individuals (6.8%) descent the fishway, with average time spent 36.6 days, the minimum and maximum time was, respectively, 7.6 and 448 days. The permeability of fish ladder is essential for maintenance of migratory species, especially long distance, providing connectivity between different areas of life (feeding and breeding), in order to maintain the fitness of these target species and its consequent conservation
