Populational biology of tilapia, Oreochromis niloticus, of Guarapiranga Reservoir, São Paulo í II. Reproduction dynamics

Abstract

Aspects of the reproduction of Oreochromis niloticus Linnaeus, 1757, of Guarapiranga Reservoir during the period of August 1996 to July 1997 were investigated. The reproductive period was determined analyzing the maturation curve, established by the variation of the gonadosomatic index, relative frequency of the maturation stages and condition factor. The reproductive period extends from September to December, and the spawning is of the fractioned type. The size of the first sexual maturation was estimated in 76 mm, corresponding to the first year of life.