Indicadores reprodutivos de Parauchenipterus striatulus (Steindachner) (Pisces, Auchenipteridae) na Represa de Ribeirão das Lajes, Rio de Janeiro, Brasil

Abstract

Parauchenipterus striatulus is a representative of the freshwater catfish with wide distribution in the South America region. Despite of being a very abundant fish in rivers and reservoirs of this region, little is known about its biology and ecology. In Ribeirão das Lajes reservoir (22º42'S - 22º50'S, 43º53'- 44º05' W, Rio de Janeiro), the Rio de Janeiro state's largest hydroelectric reservoir, this species is very abundant, representing about 40% of the total experimental fish catches using gill nets. This paper aims to assess aspects of the reproductive cycle of this species describing the gonadal stages, gonadosomatic index, weight-length relationship and condition factor. Fish sampling were carried out bi-monthly, between April 1996 and May 1997. Gill nets used were 100 m long, 4 m high with mesh size between 25 and 65 mm. Macroscopic analysis of 339 individuais were performed for the determination of 5 maturation stages, for both sexes (immature, maturation I, maturation II, ripe, spawned (females) and emptied (males). The gonadosomatic index for both sexes was higher from October to March, suggesting a long spawning period while the condition factor was higher from February to June, showing an inverse relationship between these two parameters. Weight-length relationship for males was W=0,0095L3,C862and for females W= 0,0116L3,126, and no significam differences were shown between sex with reference to the alometry coefficient.