Reproductive Cycle of Edible Echinoderms from the Southwestern Indian Ocean II. The Ssandfish Holothuria scabra (Jaeger, 1833)

Abstract

The reproductive cycle and gonad morphology were investigated in a population of Holothuria scabra (Jaëger, 1833) from Toliara, southwest of Madagascar. Surveys were done from November 1998 to April 2001 by monthly samplings of 30 individuals. There is a single gonad formed by a tuft of numerous ramified tubules. The annual reproductive cycle of the population was determined from monthly variations of the gonad index and the maturity index. Five sexual maturity stages were described. An annual reproductive cycle occurred with most individuals being mature or spawning between November and April. Gametogenesis was not synchronous in the population, but was synchronous in all the tubules of a single gonad except the smallest immature ones (length < 1 cm). The length of tubules is not uniform in a gonad, and the number of gonad tubules is related to the size of the animal. Each tubule had a clear annual cycle, being the smallest in recovery gonads (regressed tubules) and the largest at the end of the maturation period (developed tubules). Recruitment of new tubules appears to occur throughout the year. Observations made suggest that the newly recruited tubules remain immature up to the beginning of the next reproductive cycle.