Fecundity and fertility of Macrobrachium amazonicum (Crustacea, Palaemonidae)

in brazil, studies with native freshwater prawn species were discontinued due to great importance of macrobrachium rosenbergii. therefore, it is necessary to continue investigations about our species, in order to develop technology adequate to our reality and in a future allow prawn farmers to culture other species. the aim of this study was to determine the fecundity and fertility of macrobrachium amazonicum captured monthly from june 1999 to june 2001 from jaguaribe river, itai？aba, ceará, brazil. prawns were collected using fishing net and transferred at biological science laboratory, ceará state university (fortaleza, ceará, brazil). among the ovigerous m. amazonicum females, 60 were randomly selected to determine fecundity. the eggs adhered to the pleopods were taken out and they were then placed in a gilson solution, and then stored in alcohol 70%. individual fecundity was determined from the total egg counting, using a stereoscopic microscope. to determine fertility, ovigerous m. amazonicum females were stored in individual 10 l-glass tanks maintained under strong aeration. after the hatching, the larvae were siphoned and counted. the data referring to total length and weight of all the females, storage date, coloration and number of eggs, weight and coloration of gonad and number of hatched larvae were noted. with respect to average fecundity (f) by length classes, the lowest and highest number of eggs observed was 696 and 1,554, respectively. as for fecundity by weight classes, the lowest number of eggs observed was 760 and the highest, 1,690. the highest number of eggs observed individually per hatching was 2,193. average fecundity/total length (l) and average fecundity/total weight (w) may be expressed by a linear relationship. the adjusted equations are: f = -411.6 + 203.1 l (p < 0.0001) and f = 566.4 + 157.3 w (p < 0.0001), respectively. in the analysis of average fertility (n) per length classes, the lowest and highest number of larvae observed was 374