Migration of Curimba Prochilodus lineatus at Volta Grande and Igarapava Reservoirs, Grande River, Brazil

The curimba is a Characiformes, Prochilodontidae, distributed in the Paraná-Paraguay Rivers basin. It is considered to be a large distance migrant. Studies developed in the 1950’s have showed that curimba could migrate up to 1.000 km in the system of the Mogi-Guaçu/Pardo/Grande Rivers using the Mogi-Guaçu River as a spawning site and the Grande River as a feeding site. In the 1970’s several dams were built at the Grande River blocking the migration route for this species. So, this study evaluated the migratory behavior of curimba in two different reservoirs at Grande River, connected by a fish ladder. To accomplish that we radio-tagged 30 adult curimbas with a 10 g Lotek® coded radio tag with the antenna extending outside the body. Fish were captured just below Volta Grande Dam and released in the reservoir 7.5 km upstream of the dam. Fixed data-logging radio telemetry receivers were used to track movements of tagged curimba in the forebay and in the tailrace just below Volta Grande and Igarapava dams, and in the tailrace below Jaguara Dam. Also, fish were manually tracked using a boat-mounted tracking system to survey the reservoirs. Data suggested the following conceptual model for curimba migration at Volta Grande and Igarapava reservoirs: fish passed upstream Volta Grande Dam migrate upstream, dispersing through the reservoir. About 45% reached the tailrace are of the Igarapava Dam where they staged for a few weeks up to 16 months. The majority of curimba that staged at Igarapava tailrace (70%) passed through the fish ladder migrating upstream through the reservoir. They spent 1-6 hours to traverse the ladder, passing 14-87 tanks/h. After passed upstream they spent 12 min to 5 h to left the forebay of the Igarapava Dam and continue their migration until they reached Jaguara tailrace were they remained till the last track. These results suggested that curimba still use the Grande River for dispersal migrating upstream. No downstream movements were recorded.