Populational studies of Macrobrachium birai Lobão, Melo & Fernandes e de Macrobrachium petronioi, Melo, Lobão & Fernandes from Cananéia and Juréia regions (SP í Brazil) : I. Dynamics of reproduction

Abstract

The objective of the research was to know the reproductive dynamics of Macrobrachium birai and Macrobrachium petronioi populations from Rio Branco (Cananéia - SP) and Rio Verde (Juréia - SP) with the purpose of supplying post-larvae in re-stocking operations. Monthly captures were realized from July/1985 to March/1988 and September/1987 to August/1990, respectively. The reproductive period was determined through the seasonal relative frequency variation and the average gonadosomatic index of females in reproductive period. The results indicate that the major reproductive intensity of M. birai from Cananéia and M. birai and M. petronioi from Juréia was during the summer, while M. petronioi from Cananéia had its reproductive period in winter, spring, and summer, with accentuation in spring. The average size of first sexual maturation was 4.00 - 4.50 cm for M. birai and 3.50 - 4.00 cm for M. petronioi from Cananéia. In Juréia it was obtained the class of 3.00 - 3.50 cm for M. birai and M. petronioi. It has been verified the predominance of males in all studied populations, being this aspect more intensive for M. birai populations. The differences were attributed to intrinsic factors of each studied region: in Juréia it was verified the occurrence of mountain range climate and in Cananéia the Iittoral climate is predominant.