Solar-dried kelp as potential feed in sea urchin aquaculture

Over the past two decades, fishery landings for the highly valued green sea urchin (Strongylocentrotus droebachiensis) have decreased significantly in the Gulf of Maine. Methods for sea urchin aquaculture have been developed in the region, but further growth of the industry is inhibited by the expense of formulated feeds. A potential low-cost solution to this issue is to take advantage of the region's developing sea vegetable aquaculture industry. A feeding trial was conducted with juvenile hatchery-reared urchins comparing somatic and gonadal growths when fed either fresh wild Saccharina latissima, dried S. latissima, fresh laboratory-reared Porphyra umbilicalis, or the formulated Nofima diet. Somatic and gonadal growths of urchins fed dried S. latissima were intermediate to those fed fresh macroalgae (S. latissima or P. umbilicalis) and the formulated Nofima diet, with significantly faster growth observed in urchins fed the formulated diet and significantly slower growth seen in those fed the fresh macroalgae diets. In light of these results, we propose that dried kelp could suffice as a potential feed in sea urchin aquaculture.