Enkele gegevens over een populatie van Haliotis Tuberculata aan de Franse Middellandse Zee-Kust

An investigation on distribution and abundance of Haliotis tuberculata in a small bay near Banyuls-sur-Mer (Pyrenees Orientales, France) showed that a minimum of 4000 individuals of H. tuberculata were living on a surface of approximately 1600 m². The distribution of ormers was clustered; certain stones seemed to be preferred. Empty shells founds near Banyuls were in general larger than the shells of living animals. It was calculated that the risk of dying increased enormously when H. tuberculata grew bigger than 25 mm. The maximum lengths of empty shells found near Banyuls were the same as the lengths of shells found near Le Lavandou (Côte d’Azur, France) but both were much smaller than the living animals measured by Bolognari (1953) at Taormina on the Italian coast. We tried to correlate the number of growth rings (best discernable on the inner surface of the empty shell) with the length of the shell, but as counting growth rings is difficult and the interpretation of growth rings still unclear, this method was not very successful. It appeared that the growth rate of H. tuberculata found near Le Lavandou was higher than that of ormers living near Banyuls.