Reproduction of the sea cucumber<i>Holothuria leucospilota</i>in the Western Indian Ocean: biological and ecological aspects

Abstract

Summary Reproduction of Holothuria leucospilota was investigated for the first time in the Western Indian Ocean in 2005-2006 in the reef of La Réunion. Two spawning events occurred revealed by gonad index (GI) and histology. Gametogenesis of H. leucospilota was divided into five stages of maturity: resting, immature, growing, maturation and post-spawning. It was synchronous within the population and initiated in July when solar radiation increased. From July to December, the growing stage was dominant, followed by a majority of specimen in maturation in January. The first spawning event occurred in February whereas the second one occurred in May. Breeding season of H. leucospilota takes place during Austral summer when temperature and tropical rainfall reach their maximal. Between March and June, only 22% of specimens were found with a completely resorbed gonad in resting stage. 'Atresia' appeared more frequently in females in an advanced stage of maturity. In male gonad 'atresia' was only observed in the post-spawning stage. Sexual dimorphism was significantly measured in body weight, gonad weight, tubule diameter being all greater in females. An unbalanced sex ratio was skewed (17:191) towards females. Weight at the first maturity was defined for a total weight above 180 g. All of these biological aspects are relevant for the conservation of H. leucospilota species in the Western Indian Ocean that is under fishing pressure.