CONICET | Buscador de Institutos y Recursos Humanos

The redclaw crayfish, Cherax quadricarinatus, is a species of growing importance in freshwater aquaculture, in spite of which numerous aspects of their reproductive biology are unknown. The aim of this study was to characterize the differentiation and later acquisition of sexual maturity in males of this species. For this purpose 353 males (0.09-150)g were weighted, measured, dissected and their reproductive systems were fixed, cut and stained. From a macroscopic point of view, males from 0.09g up to 2-3g differentiate a lobular appendix, and from 3g they develop an elongated appendix, acquiring the longitudinal striation pattern typical of adult males. From 0.09-0.10g the reproductive system differentiates clearly like a thin lobular cord and a transparent vas deferens, whereas from 6g the testicular lobes acquire a greater size and number, the vas deferens presents a white colour and begins to differentiate the red patch in the outer edge of the chelipeds propodus. The microscopic results showed the presence of spermatozoa in the collecting tube (within the testes) from 0.09-0.10g while spermatozoa were also observed packaged in the spermatophore within the vas deferens from 2-3g. The present study shows that the differentiation of primary and secondary sexual characters in C. quadricarinatus occurs simultaneously and very early during development and that the acquisition of sexual maturity (presence of spermatozoa in collecting tube and vas deferens) is also an early event that occurs at smaller sizes than in females. The identification of sex in the first developmental stages is a very useful tool that may allow the early separation for monosex culture, as well as the development of sexual reversion techniques by means of ambient or hormonal factors manipulation. Financial support: ANPCYT (PICT 2004-953), UBACYT 2004-2007 (project X143), Antorchas Foundation (project 4248-138).

enviar mensaje