34 SEPTEMBER 2024 • WORLD AQUACULTURE • WWW.WAS.ORG on smaller, nearshore aquaculture systems that can be adopted by fishermen and support local seafood production. With this philosophy a floating IMTA platform called the AquaFort was developed to culture steelhead trout (Oncorhynchus mykiss), blue mussels (Mytilus edulis), and sugar kelp (Saccharina latissima) (Figure 2). The IMTA approach benefits the marine ecosystem by having lower trophic shellfish and seaweed species extract organic and inorganic nutrients released by the fish. A nitrogen mass balance was calculated to determine the amount of nitrogen put into the system (feed) versus the nitrogen removed at harvest. The results suggested that production and harvest of 3 tons of shellfish and seaweed combined are needed to extract nitrogen inputs for every ton of fish (Chambers et al. 2024). While it is difficult to accommodate this amount of biomass on just the platform, additional kelp and mussel farms can be deployed at the same site to meet the extraction needs. UNH also uses the AquaFort for aquaculture education, training, demonstration, and research. The small-scale system breaks down permitting barriers that face new farmers and provides a sustainable source of fresh, local seafood to coastal communities. In addition, fishermen can adopt this technology either full time or part time and site the farm in between their fishing grounds. This approach allows them to stop by the site on the way out to sea or upon their return to feed fish and maintain the farm. This type of aquaculture is ideal for remote island communities to grow a safe and reliable source of protein. The UNH AquaFort is located at a semi-protected site at 10m water depth, 400m off New Castle, New Hampshire (NH). It is In 2000, the University of New Hampshire (UNH) received support from the National Oceanic and Atmospheric Administration (NOAA) to explore open ocean aquaculture in the Gulf of Maine. This regional effort secured a 30-acre lease, 10km offshore at 52m depth. Northeast storms would frequent the exposed area with 10m high waves and 0.65m/sec currents. As a result of the high energy site, submersible culture systems were investigated and a robust, 8-point mooring grid was deployed to hold the sea pens in place (DeCew et al. 2012). Engineers and biologists worked together to design systems that could survive offshore and grow seafood to supply local demand. The project successfully evaluated several farming systems (Sea Station, Aquapod and OCAT), (DeCew et al. 2013; Chambers et al. 2011, 2007, 2003; Fredriksson et al. 2004) that grew cod, haddock, halibut, and steelhead trout (Chambers et al. 2012, 2006, Rillahan et al. 2011, 2009). Mussels and scallops were also cultured on submerged long lines adjacent to the fish farm (Langan et al. 2003). The project team designed and constructed a remotely operated feed buoy with 20-ton feed capacity, that was controlled from campus and an environmental monitoring buoy was deployed to provide real time oceanic information to researchers, students, and fishermen (Figure 1). Fish growth was slow, and it took 3 years for cod and 5 years for halibut to reach market size in this environment. This duration of grow-out and prevailing market prices created economic challenges for these particular species in offshore conditions. Integrated Multi-trophic Aquaculture (IMTA) Since the Open Ocean Aquaculture project, UNH has focused AquaFort, a Floating, Integrated Multi-trophic Aquaculture System Michael D. Chambers, Michael Coogan, Michael Doherty, Erich Berghahn and David W. Fredriksson FIGURE 1. Diagram of the University of New Hampshire’s open ocean aquaculture farm in the Gulf of Maine. FIGURE 2. A diagram of the AquaFort that cultures steelhead trout, blue mussels, and sugar kelp. The lower trophic species extract organic and inorganic nutrients from the fish.
RkJQdWJsaXNoZXIy MjExNDY=