Integrated multi-trophic aquaculture of steelhead trout, blue mussel and sugar kelp from a floating ocean platform

Abstract

Over the last several decades, the commercial fishing fleet in New England has been subjected to increasingly restrictive management measures established to rebuild declining stocks. This has limited fishing opportunities and significantly reduced the inshore small vessel fleet. To help support New Hampshire (NH) commercial fishermen, an extension program was developed by the University of New Hampshire (UNH) and NH Sea Grant to train fishers on small-scale integrated multi-trophic aquaculture (IMTA) growing steelhead trout, blue mussels, and sugar kelp together, with the goal of providing alternative income sources and increasing local food production without adding significant levels of nitrogen to the environment. A total of 416 kg of steelhead trout, 3072 kg of blue mussels, and 638 kg of sugar kelp were produced in this study. The steelhead trout released an estimated 25.1 kg of N into the environment, while the mussels and kelp together extracted an estimated 41.5 kg N for a net reduction of ∼16.4 kg N from the ecosystem. There was no observed negative impact on local water quality at any point during the trial. Overall, this program demonstrated a culture method that can positively impact the ecosystem, while providing the fishermen with a new skill set that they could adopt either part time or full time, to provide additional income.