Estimation du stock naturel d'ormeaux (Haliotis tuberculata) dans la region de Saint-Malo.

Abundance and biomass of an unexploited ormer population in the vicinity of Saint-Malo (northern Brittany) are estimated using a stratified sampling technique. Examinations are made be diving at 200 sites. The mean biomass of the population is about 400 tons but the stock is not evenly distributed over the studied area: the greatest densities are observed on schist substrate. Size and weight frequency distribution reveal a "top-heave" structure due to an accumulation of old individuals with low production.