Reproductive performance of male Argentine red shrimp Pleoticus muelleri bate (Decapoda, Penaeoidea) in culture conditions

Spermatophore and sperm quality of male Argentine red shrimp Pleoticus muel leri held under laboratory conditions was evaluated using compound spermato phore weight, sperm count and percentage of live sperm as indicators. Thirt y-seven males of 5 to 20 g wet weight were held indoors in a 3-m diameter c ircular fiberglass tank for 45 d. They were fed fresh squid, clam and pelle tized diet. Spermatophores were obtained by manual ejaculations. Four shrim ps were re-ejaculated to verify the subsequent spermatophore regeneration. Spermatophore mean weights were significantly lower for 5-10 g males than f or 15-20 g males (r = 0.998) (P < 0.05). There were no significant differen ces in sperm count and percent live sperm among the different weight classe s (5-15 g, 15-20 g, 20-25 g). The sperm count varied from 2.22 to 5.62 mill ion. No change in sperm quality was seen in re-ejaculated individuals. Duri ng the first 2 wk of the experiment, the spermatophores exhibited healthy m orphology and colour; by the fifth week evidence of spermatophore deteriora tion was apparent. Despite the degree of melanization, sperm quality was no t affected and the high variability in sperm count indicated that the artif icial ejaculation is adequate in this species.