The effect of electrical stimulation on spermatophore regeneration in white shrimp Penaeus setiferus

Abstract

The effect of electrical stimulation on the quality of P. setiferus sperm cells was studied during the regeneration of the spermatophore. The proportion of the animals that responded to electroejaculation was quantified and the number of live, abnormal and dead cells, as well as the relationship between the number of cells and body weight, were taken into consideration as indicators of the effect of manipulation during stimulation. It was found that electrical stimulation caused some degree of spermatophore expulsion in 78% of the cases. Total expulsion of the spermatophores occurred in only 8.3% of the cases. A logistic curve was adjusted to the relationship between the number of sperm cells and the weight of the shrimp. After regeneration no curve was adjusted to the relationship. Eighty per cent of the stimulated shrimp regenerated the spermatophore in a maximum of 168 h. Fifty per cent regeneration was obtained in 96 h after stimulation. A decrease in the number of live cells from 26.8 to 7.6 million and an increase in abnormal (from 0.02 to 3.92 million) and dead (from no cells dead to 4.6 million) respectively, were registered for regenerated animals. Necrotic areas in 60% of the ampulae of regenerated shrimps were also observed. Bacteria associated with the necrotic ampulae was observed when counting sperm. As the spermatophore of this species is complex, it is necessary to search for a way to reduce the stress produced by the handling of the ampulae so as to avoid altering the reproductive capacity of the shrimp.