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Different incubation techniques for yolk sac larvae of Atlantic halibut (Hippoglossus hippoglossus L.) were compared and evaluated on the basis of survival and amount of normally developed larvae. The three investigated incubator concepts were; 3-litre glass-bowls maintained with stagnant water, 100-litre flat bottom PVC-tanks run with slow water exchange, and 350–1450 litre flow through silos with up-streaming water. The survival at the end of the yolk sac stage in 3-litre bowls was 30–90%, and increased reproducibility was obtained by addition of 25 ppm antibiotics to the water at start of the incubation. In the PVC tanks the survival was lower (20–55%). The flow through silo-incubators with up-wards water flow gave survival of 30–70%, and exhibited the highest reproducibility in survival for replicates. The fraction of normally developed larvae ready for first feeding varied both with larval batches and incubator-type. For all batches of eggs, lowest amount of normal larvae were obtained in the 100 litre PVC-tanks. In the bowls and the silos the fraction of normal larvae were 55–75% in the investigated batches. The most dominating deformity was jaw deformity (gaping), and lowest relative fraction of gaping was obtained in the bowls and in silos in larval batch 2. An overall evaluation of the incubator potential of efficient large scale production of yolk sac larvae ready for first feeding suggests that the silo-incubators have the highest potential.

New consumer trends, market demands, and opportunities for multiple uses of macroalgae such as food, bioactive components for functional food and feed ingredients, fertilizers, and biofuels have strengthened the motivation for industrial macroalgae cultivation in Europe. The cultivation of kelp in sea requires production of seedlings on substrate to be deployed at sea farms. There are three main strategies for seedling production of kelp, aiming for seeding of the growth substrate with spores, gametophytes, or small sporophytes, whereof seeding with spores and gametophytes so far is the most incorporated techniques. Seeding with spores requires fertile sporophytes and this is seasonally dependent if these are collected in natural habitats, but fertility can also be induced by artificial day rhythm, and thus enables access to spores independent of natural seasons. Gametophytes can be kept in continuous cultures and be available for year-through seeding or production of microscopic sporophytes for direct seeding. This is advantageous as the use of incubation facilities on land can be shortened by several weeks or, in the case of direct seeding, omitted completely. The presented protocol focuses on Saccharina latissima seedlings production from spores and gametophytes and is adapted to the infrastructure and equipment that are available at typical aquaculture research laboratories, although some adjustments may be necessary to meet the needs of the different life stages. Keywords: Saccharina latissima, cultivation, seeding, laboratory protocol, gametophyte cultures, contamination control, deployment