(Aspects of the populational structure and reprodutive period of the "tambiú” Astyanax bimaculatus [Characiformes, Characidae] in Bariri Reservoir, Tietê River, São Paulo State, Brazil)

Abstract

In this paper, 2,070 specimens of "tambiu", Astyanax bimaculatus, caught in Bariri reservoir during the period of January, 1978 to December, 1982, were analyzed. The objective was to study aspects of populational structure in distinct seasons of the year and reproductive period. The results indicated that the proportion sex ratio was about 1:1, significant to leveI of 5%. The females attain superior length in relation to males and they are predominant in the larger length classes. It was observed that the reproduction happens in spring and summer, with maximum reproductive intensity in spring. The relationship between total length and body weight, determined to males and to females, resulted: males W = 0.0079 L^3.2489 and females W = 0.0168 L^2.9872.