Identification of spawning sites and natural nurseries of fishes in the upper Paraná River, Brazil

• DOI: 10.1007/s10641-004-0098-z
• Publication Date: 2005-01-12T13:34:35Z
• Authors: Gilmar Baumgartner; Keshiyu Nakatani; Luiz Gomes; Andréa Bialetzki; Paulo Sanches
• Keywords: Parana river

We studied the timing of migratory fish spawning in the last dam-free stretch of the upper Parana River and in Itaipu Reservoir. Eggs were more common in the Amambai and Ivai Rivers, while larvae predominated in the Parana River and in Itaipu Reservoir. Both eggs and larvae were more abundant at night. The highest abundance of eggs was in October and that of larvae in November. Migratory species predominated in the Amambai and Parana Rivers, and non-migratory species in the Ivai River and Itaipu Reservoir. The predominance of eggs in the upper and middle portions, and larvae in the lower, infer that there are spawning sites in the former and nurseries in the latter. The high nocturnal abundance of eggs is associated with spawning at sunset and that of larvae with feeding, avoidance of predators and nocturnal disorientation. The presence of tributaries such as the Amambai and Ivai Rivers in the last dam-free stretch of the Parana River is extremely important to the maintenance of regional fish diversity and fish stocks in both the Parana River and Itaipu Reservoir.