Reproduction and growth of Sphaerechinus granularis (Echinodermata: Echinoidea) in southern Brittany

Abstract

Although the English Channel is the northern limit of the latitudinal range of Sphaerechinus granularis (Echinodermata: Echinoidea), this echinoid can produce locally high densities in Brittany, such as in the Glénan Archipelago (Bay of Concarneau) where a small-scale fishery has been exploited since 1985. The reproductive cycle, the growth patterns and the migration of the species in this area were studied from 1988 to 1992. Sphaerechinus granularis presents an annual reproductive cycle with a major spawning in the early spring. But inter annual variability in the time when spawning starts can be observed. A relationship is established between the date of onset of spawning and the climatic conditions during the whole period of gonadal growth. Recruitment is isolated in time and reflects the reproductive cycle.