WWW.WAS.ORG • WORLD AQUACULTURE • SEPTEMBER 2024 35 totally exposed to Southeast storms and has endured waves up to 5m and currents of 0.65m/sec. The current farm model can produce 15 tons of seafood. If the culture system were taken to deeper waters (25m), nets and mussel droppers could be extended to double production. The size of the farming system makes it user-friendly for first-time farmers with vessels less than 10m in length. The next iteration of the AquaFort will have modular net bays that can be added or modified to increase growout capacity. This will allow farmers to increase production once they have trained on a smaller system with less investment. The UNH IMTA farm draws many students, teachers, researchers, fishermen and entrepreneurs that have interest in growing seafood. Chefs and wait-staff visit the farm to learn about IMTA. They then share this information with customers at their restaurants. People really enjoy it when seafood is grown locally in their backyard. Visitors to the farm range from 250- 300/year. We have trained 16 fishermen on the AquaFort model and hope to see this type of aquaculture spread to different states with larger coastlines. Permitting is always a challenge but this can usually be overcome with patience and perseverance. In fact, the Gulf States Marine Fishery Commission has funded an AquaFort IMTA project near Dauphin Island, AL. The team members are Dauphin Island Sea Lab, University of Southern Mississippi, and the University of New Hampshire. The project is in the permitting phase with plans to deploy an AquaFort later this year for sea trials. The system will be stocked in 2025 with red drum (Sciaenops ocellatus), eastern oyster (Crassostrea virginica) and gracilaria (Gracilaria tikvahiae) for a winter/spring growout. Seafood Growout Species grown at the UNH AquaFort are sourced locally. Juvenile rainbow trout (200-300g) are purchased from Sumner Brook Trout Farm in Ossipee, NH. For one month before stocking, they are fed a modified transition diet with added salts to develop their chloride cells and ease their acclimation. The fish are stocked directly from fresh water into salt water in the fall at 2000 fish/pen and a stocking density of 2kg/m3 (Figure 3). Winter growout is desired as summer temperatures reach 20-22oC which can be stressful for the juvenile trout. Trout introduced to the farm in the fall, with cooling temperatures, acclimate better to the marine environment. Steelhead trout are sold to local markets in Portsmouth, NH for $13-20/kg at a mean size of 2 kg. Mussels naturally recruit during fall and spring (when temperatures reach 14oC) and settle onto 3m long dropper lines that are suspended from the HDPE outer frame. It takes them 16-18 months to reach a market size of 55mm where they can be sold for $6.60/kg. Broodstock kelp from the Gulf of Maine is spawned in a hatchery with seed set onto stringline. After 2 months of onshore growth, the juvenile kelp is transferred to the site in November and attached to vertical dropper lines suspended from the AquaFort. The seed line is also wrapped around horizontal growout lines (75m long) next to the IMTA system. This winter crop is harvested in the spring at a length of 3-4m and at a biomass of 10-12kg/m (Figure 4). Kelp has been provided to local breweries that craft an amber beer called Selkie. Working with Fishers An important aspect of the AquaFort IMTA project has been engaging fishermen on this novel technology. Overfishing in the northwestern Atlantic has led to the depletion of bottom stocks. (Willert et al. 2023). In addition, changing fish quotas and new regulations make it difficult for fishers to stay in business. Some of the fishermen have switched to lobster fishing that has been prosperous thus far. However, this could change with climate change and increased temperatures in the Gulf of Maine, as well as increasing bait and fuel costs. Over the years, numerous fishermen have visited and trained on the farm. Several groups are investigating permits in Maine. This process is often challenging and highly variable between different states. UNH is working with other states to share the IMTA permitting process that has worked in NH. We hope to see more of these systems permitted in coastal communities to provide fresh, locally produced seafood and reduce the carbon footprint associated with imported seafood to the U.S. Next steps Recent funding from a NH donor has allowed IMTA research to continue for 3 more years and helped to establish the UNH Center of Sustainable Seafood Systems. Research will include the addition of instrumentation inside and around the system with real time communication. We want to measure the water flow and mixing FIGURE 3. Steelhead trout circling within the AquaFort before feeding. (CONTINUED ON PAGE 36) FIGURE 4. Harvested seafood from the AquaFort including steelhead trout, blue mussels, and sugar kelp.
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