The SMARTTANG project (2022–2025) aimed to develop, test, and document scalable cultivation strategies for sugar kelp (Saccharina latissima) using tube and net-based systems adapted from existing nearshore mussel aquaculture infrastructure.
Through systematic hatchery trials, testing different seeding techniques and net materials (nylon, polyester, polypropylene) a final seeding was made, seeding five 50 m nets with a depth of 1.2 m with S. latissima. The nets were deployed in a commercial mussel farm in Limfjorden, Denmark. The field trials documented, that the biomass yields were controlled by depth and vertical/horizontal deployment orientation: Nets deployed horizontally near the surface achieved the highest yields, with up to 13.2 ± 2.4 kg fresh weight m-2, compared to 7,2±0,7 - 8,4±0,3 kg m-2 on vertically oriented nets and 4,9±0,5 kg m-1 on a horizontal line. The biomass quality was suitable for food, feed, and biorefining applications, though iodine concentrations and biofouling increased markedly toward harvest in late April, underscoring the need for early harvest.
Trials were conducted for harvesting kelp of the nets testing existing mussel harvesting equipment, but it was apparent that technology development was needed to effectively harvest the nets. The harvested biomass was processed at a large scale facility using a screw press and a microcutter to obtain a biomass slurry, which was readily fermentable with addition of a lactic acid bacteria inoculum. The fermented biomass stored well, and was still useable and pH stable after 1 years of storage, after which it was tested in a commercial scale setting as feed for pigs. The raw biomass was also used for development of a new snack for kids, which was evaluated within the project.
Finally, a complementary sustainability assessment integrating Life Cycle Assessment and Techno-Economic Analysis compared net-based systems with conventional longline cultivation. While net systems achieved high area-specific yields, longline systems showed substantially lower material intensity, greenhouse gas emissions and higher economic performance.
Overall, the SMART TANG project demonstrated that S. latissima, can be produced on tube-net systems, and used for food and feed, but longline systems currently remain superior in terms of environmental footprint and economic viability. The results provide concrete guidance for seaweed producers, technology developers, and policymakers seeking to scale-up nearshore kelp cultivation in European waters.