CULTIVATION OF THE AUTOCTONOUS SEAWEED Laminaria saccharina OFF THE GALICIAN COAST (NW SPAIN): PRODUCTION AND FEATURES OF THE SPOROPHYTES FOR

The production and characteristics of the sporophytes for an annual and biennial harvest were studied in a cultivation of Laminaria saccharina ('sugar kombu') carried out off the Galician coast (NW Spain). For the indoor production of seedlings attached to string the European technique developed by the French Fisheries Institute (IFREMER) was used. This technique has been adapted by the Spanish Oceanographic Institute (IEO) for this species. The string with the L. saccharina seedlings was outplanted in cultivation ropes which were deployed horizontally ('longline') in the sea, in February 2002. Productivity was about 6 wet kg m-1 culture rope for annual-harvest and 4 wet kg m-1 for biennial-harvest, after 4 and 13 months respectively. The decrease in the harvestable biomass (about 35 %) came as a result of a striking reduction in the number of plants on culture rope between both crops, probably because of high mortality of sporophytes throughout the summer. The results on blade features of L. saccharina showed important differences between annual and biennial harvests which affected the "substantiality value " rate that expressed the quality of blade for food for human consumption used in Asia. Substantiality value of L. saccharina was 36 mg cm-2 wet weight of blade for annual-harvest and 61 mg cm-2 for biennial-harvest. Another aspect which needs to be highlighted was the high cost of the biennial harvest due to the necessary maintenance practice of this cultivation