Аннотация:The ormer, Haliotis tuberculata L. is a greatly prized species in the Channel Isles. Since the original survey of the ormer population of Guernsey and the subsequent tagging experiments (Forster, 1962, 1967), periodical short visits to the island have been made to investigate the stocks of ormers, especially in areas fished by divers; in 1968 and 1974 visits were also made to Jersey. These surveys were all made at the request of the local Sea Fisheries Committee. In this paper we seek to bring together those aspects of the results which are of scientific interest and to discuss the role of various factors which may have affected the ormer populations particularly that of changes in temperature over the last hundred years. The reproductive biology of this species has recently been reported on by Hayashi (1980).