Sperm viability in wild-caught males of Macrobrachium tenellum (Smith, 1871) (Decapoda: Caridea: Palaemonidae) fed with different diets

Abstract The relationship of body weight and length with sperm load and spermatophore weight was evaluated in wild males of Macrobrachium tenellum (Smith, 1871). In addition, the influence of a commercial and natural feed on the load and viability of sperm was determined in wild males. In 28 wild males spermatophore extraction was performed by electrostimulation 24 h after capture to analyze the relationship between body length/weight and sperm load and viability, respectively. Spermatophore weight (SW), total number (TS), dead (DS) and abnormal sperm cells (AS) were used as indicators of sperm viability. The results obtained show that there is a positive correlation between TS per spermatophore compared to body length and weight of the male. To study the effect of different diets on sperm load, three diets were employed: Diet A, commercial shrimp feed; Diet B, natural feed (mixture of squid, sardine and clam); and Diet C, combination of natural and commercial diet. To assess the initial reproductive status of the males at the beginning of the experiment, sperm viability was determined in a subsample of specimens after capture. Broodstock were fed ad libitum once a day during 70 days. TS, DS, AS and SW were evaluated. The results of the bioassay did not show differences between treatments in the parameters analyzed, except DS, which was higher in the initial group. In conclusion, the present work suggests that it is feasible to substitute fresh feed for an artificial diet for the maintenance in captivity of male M. tenellum broodstock shrimp.