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UNH-led Team Designs Aquaculture Raft to Provide Four-Season Source of Seafood and Sea Veggies

Integrated Multi-Trophic Aquaculture in New England

By Rebecca Zeiber, New Hampshire Sea Grant

The Piscataqua River is home to a new piece of equipment: an aquaculture raft intended to provide a four-season source of local fish and shellfish, increasing revenue for struggling N.H. fishermen while removing excess nitrogen from the water.

The raft, designed by a University of New Hampshire team including graduate student Corey Sullivan (UNH ’14) and UNH ocean research engineer Matthew Rowell (UNH ’13G), will house steelhead trout, blue mussels and sugar kelp potentially valued at $70,000 annually. UNH researchers, N.H. commercial fishermen and an in-state manufacturing facility collaborated for almost a year to design the raft, which was deployed in the river on Aug. 24, 2015.

The double-bay, 7,500 pound raft was transported in two halves on a flatbed truck from its manufacturing facility, JPS Industries, in Bristol, N.H. When it arrived at the pier, the two halves were then bolted together. Among the individuals helping out were project leaders Rob Swift and Barbaros Celikkol (UNH professors of mechanical and ocean engineering) and Michael Chambers (NSHG/UNHCE marine aquaculture specialist). Once assembled, the raft was then lifted into the water and moored to the pier where it now awaits additional construction to accommodate a walkway around the edge and a framework to hold the fish pens and mussel lines. 

“It was surreal to see it come together, to see the full scope of it in held up the air by that crane after looking at it for so long on a computer screen,” Sullivan said. “I was really happy when it sat just how I wanted it to sit in the water,” he added.

Sullivan, Chambers, and 2015 Doyle Fellow Megan Peavey (UNH ’16) are currently constructing the wooden-planked walkway on top of the raft and attaching the stanchions to the frame. Construction should be finalized in the coming weeks, and the raft will then be towed out to the UNH aquaculture site in the mouth of the Piscataqua River near Fort Constitution. Chambers hopes to train more fishermen and aquaculture entrepreneurs from N.H. and Maine in the upcoming year.

This project is an example of integrated multi-trophic aquaculture (IMTA), whereby two or more species that occupy different parts of the food chain are grown in the same area. The advantage of employing IMTA over traditional aquaculture methods comes by way of waste products; fish excretions can be used as fertilizer or food for the other species growing around the raft.

This project is a “dream come true” for Chambers and Hunt Howell, UNH professor of biological sciences, who have been exploring IMTA for the past four years with the old cage infrastructure. 

Historically, it has been difficult for fishermen to obtain the necessary aquaculture permits due to concern over pen-raised fish waste adding nutrients to waterways that already have too much nitrogen. This has been a major impediment to the growth of the aquaculture industry in New England, Swift said, but IMTA is helping to change that.

“In addition to being environmentally sustainable, the use of IMTA methods will expedite the process for fishermen to obtain permits,” Swift said. “This technology is readily transferable to other New England states in its present form, and the concept is transferable to all U.S. coasts and worldwide,” he added.

Funding for this project was provided by a grant from the NOAA Saltonstall-Kennedy Grant Program and by N.H. Sea Grant. For more information, please contact Michael Chambers at or Rob Swift at

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