The Japanese brown alga Undaria pinnatifida on the coast of France and its possible establishment in European waters

The first observations of the seaweed Undaria pinnatifida (Harv.) Sur. in France were made in 1971 in the Etang de Thau in the Mediterranean, after the alga had been accidentally introduced with oysters from Japan. Since the species is of commercial interest, the prospect of cultivating it on the French Atlantic coast was explored. The risk of its dispersal from the farm site was considered minimal by the French authorities. Field experiments with farming on ropes have been conducted by IFREMER at three sites since 1983, two of which were soon abandoned. On the island of Ouessant, Brittany, the experiments with rope cultivation in the field have continued with plantules raised in a local hatchery. It was suggested that a control programme including a study of the main grazers should be carried out by French algologists.