In 2023, the U.S. seafood trade deficit was $20.3 billion, importing both capture fishery and aquaculture products mostly from Canada, Chile, India, Indonesia and Vietnam. With U.S. capture fishery production of $5.6 billion, responsible aquaculture has the potential to close this difference. The University of New Hampshire (UNH) is addressing this issue through the Center of Sustainable Seafood Systems (CSSS) by developing innovative production technologies and practices through interdisciplinary research. This presentation will provide a scientific and engineering overview of these practices at four permitted aquaculture sites along the NH coast.

The most extensive effort is being conducted at a nearshore site off New Castle with the operation of a community-scale, integrated multitrophic aquaculture (IMTA) system. The concept of IMTA is to employ the culture of high valued fed species, alongside non-fed, extractive species at biomass levels to offset the input of nutrients while enhancing the growth. The IMTA approach is to produce and harvest steelhead trout (Oncorhynchus mykiss), together with blue mussels (Mytilus edulis) and sugar kelp (Saccharina latissima) to remove nutrients. With such field operations, detailed datasets are being collected to examine the biological, chemical and physical processes associated with the IMTA method. The datasets include steelhead trout feed input trout, growth, harvest and sales from our present operational cycle. A moored, oceanographic buoy has also been deployed in this last year to acquire water quality information to include temperature, salinity, dissolved oxygen, chlorophyl, pH, nitrate, fluorescent dissolved organic matter, and current velocities. Part of the assessment is to analyze the total ammonia nitrogen entering the system by feeding the fish. With proximate analysis results, the amount of particulate organic nitrogen removed by mussels, and dissolved nitrogen removed by kelp, can be calculated. This information is being utilized to size the IMTA farm to match the biomass of extractive species with that of the fed species. Waves and current velocity profiles are also being measured at the site and are being used with loadcell datasets to validate numerical models of the IMTA structure for more accurate future design efforts.

Research is also being done at the other three permitted aquaculture sites. One of these aquaculture permits was obtained with the Seacoast Science Center in Rye to provide community education and outreach. At another one of the sites, adjacent to Appledore Island, whale safe gear for kelp farming is being field tested. The fourth site is 130 acres, 2.5 miles offshore of Jenness Beach, in a depth of 35 m. At this fully exposed location, novel aquaculture systems for mussels, scallops and seaweed are being designed to withstand the rigors of extreme storms and to minimize risk to whales that frequent the area.