Final oocyte maturation, spawning and mating in penaeid shrimp

Abstract

Final oocyte maturation, spawning, mating, and their interrelationships, differ significantly between open-thelycum and closed-thelycum species of penaeid shrimp. In open-thelycum species, mating occurs some 2 h before final oocyte maturation and spawning, following vitellogenesis, but precedes vitellogenesis in closed-thelycum species. Final maturation and spawning of commercially reared penaeid shrimp are often induced by factors such as temperature shock, filtration of seawater or darkness. In addition to these factors, mating behaviour and spermatophore transfer directly trigger final maturation and spawning in species with an open thelycum. Final maturation and spawning are also induced by seawater irradiated with ultraviolet light in Penaeus japonicus and by diets containing EPA (a precursor of prostaglandin) and vitamin E in P. monodon. These findings suggest that final maturation and spawning may be induced by prostaglandin(s), that originate from EPA and whose secretion is stimulated by water borne products of UV irradiation.