A comparison of potential yield and production timing for sugar kelp (Saccharina latissima) between sites in the north and south of Norway

Abstract Seaweed aquaculture has experienced significant expansion in recent decades, with global production reaching 34.7 million tonnes in 2020, driven by advancements in cultivation techniques and diverse commercial applications. Europe, and Scandinavian countries such as Norway, are seeing increasing interest. Norwegian seaweed farming is concentrated in the south, and although it faces unique challenges in the north it also has growth potential in northern sites. In this study, a comparison was made of growth rates and biochemical composition of Saccharina latissima grown on farms in southern (Bergen) and northern (Tromsø) Norway. Although, Bergen experiences higher temperatures but less daylight availability than Tromsø, the mean length of S. latissima sporophytes at the two sites did not show a statistically significant difference. Despite generally similar biomass production between the two sites, biochemical analysis revealed significant differences in protein and tissue nitrogen content, with Bergen having higher levels. Iodine content was not significantly different between the sites. This study showed relatively high single-season yields in both Bergen and Tromsø, with Tromsø potentially higher if optimal protocols are followed. Environmental factors like light and temperature significantly affect yields, with faster growth in the north most likely due to the 24-h light periods and northern sites also experience delayed biofouling. The study suggests strong commercial potential for seaweed aquaculture across Norway, with regional differences that can be strategically exploited.