Development of an All Season, Integrated Multi-Trophic Aquaculture Raft

Corey Sullivan, University of New Hampshire, Durham


An aquaculture floating platform to support the growth of steelhead trout (Oncorhynchus mykiss), blue mussels (Mytilus edulis) and sugar kelp (Laminaria saccharina) was developed for small operator use in waters with ocean exposure, such as the mouth of Portsmouth Harbor, NH. The raft was designed to grow-out a maximum of two tons of finfish between two net-pens as well as the necessary mussel and kelp mass needed to offset nitrogen output of the finfish. The raft was designed to maintain sufficient buoyancy throughout the growing season and to operate in a variety of sea states. Once designed, fabricated and deployed, an on-site observational experiment to monitor waves, currents, raft motion and mooring line tension was completed in January 2016. The finite element analysis program Aqua-FE was applied and evaluated using data obtained from the observational experiment. The raft has been deployed for more than a year and has performed very well throughout a variety of sea conditions. There have been no structural failures and user testimony indicates that the raft is stable and serves a desirable work platform. The second, successful full finfish grow-out season is about to come to completion. Mussels and sugar kelp have also been successfully cultivated on the raft. The two-bay raft has proven to be an effective design as a floating, ocean-going platform. The design components and construction methodology employed should continue to be pursued, and refined, as a viable option for similar platforms.