PORTSMOUTH, N.H. — Just off the coast of Portsmouth, a floating fish farm measuring 50 feet by 30 feet is helping researchers test what they believe could be the future of seafood production in the United States.
The offshore aquaculture facility, operated by the University of New Hampshire’s Center for Sustainable Seafood Systems, produces roughly 20,000 pounds of steelhead trout while serving as a model for expanding domestic seafood farming across the country.
“Aquaculture is farming the ocean,” said Michael Chambers, a research professor at UNH.
The fish raised at the facility are steelhead trout, a species that looks and tastes similar to salmon.
The fish begin their lives in inland facilities in New Hampshire’s Lakes Region before being transferred offshore when they weigh just a few ounces.
Researchers allow the fish to grow to about 5 to 6 pounds before harvesting them for local markets, including seafood retailers in Portsmouth and the Boston area.
A small crew regularly visits the floating farm to feed the fish by hand rather than relying on automated systems.
“One of the benefits of that, as opposed to using auto-feeders, is that we have eyes on the fish,” said research project manager Mike Doherty. “We’re able to visually see how quickly the fish are eating.”
The fish are fed a specially formulated diet designed to provide the proper balance of protein and fats.
While aquaculture can provide a steady supply of seafood, critics have long raised concerns about the environmental impact of concentrating large numbers of fish in a small area. Researchers at the Portsmouth site say they are taking steps to address those concerns.
Surrounding the floating pens are mussel droppers which are made up of the mollusks, kelp and seaweed.
This combination of organisms filter the water.
“The mussels uptake organic nutrients and the seaweeds uptake inorganic nutrients, so it’s all maintaining a healthy balance of nutrient management in the water,” said operations manager Eric Berghahn.
Researchers also conduct regular water-quality testing and maintain monitoring equipment downstream from the facility to track environmental conditions.
“We’re a very small scale here,” Berghahn said. “In this way it could be extrapolated out to a larger-scale concept for a larger operation.”
The project’s success has attracted national attention.
UNH was recently selected by the federal government to help oversee a broader effort to expand aquaculture in U.S. waters. Researchers have already helped establish a similar operation near an island off the coast of Alabama, with additional projects planned in Hawaii and California.
Chambers said the goal is to increase the nation’s ability to produce its own seafood rather than relying heavily on imports.
“Deploying aquaculture systems to be more competitive on a global basis, but to start to really produce domestic seafood, which has not really happened here in the ocean in the United States,” Chambers said.
Local seafood businesses say consumers have embraced the product.
“They love it,” said Rich Pettigrew, owner of Seaport Fish Company in Rye, New Hampshire. “It’s an alternative to other salmon and steelhead products, but it’s got the story behind it of being a local product.”
Pettigrew believes aquaculture will play an increasingly important role as wild fish populations face growing pressure and seafood demand continues to rise.
“The future of seafood is going to be aquaculture,” he said. “With the declining numbers of wild seafood and the supply and demand that we have here in the U.S., aquaculture is the future to sustain the amount of people that will eat seafood.”
Researchers say another benefit of offshore fish farming is flexibility.
As ocean temperatures continue to warm, facilities like the outside Portsmouth harbor can be relocated farther offshore or farther north, allowing operators to maintain conditions that are better suited for fish growth.
This is a developing story. Check back for updates as more information becomes available.
Download the FREE Boston 25 News app for breaking news alerts.
Follow Boston 25 News on Facebook and Twitter. | Watch Boston 25 News NOW
©2026 Cox Media Group
/cloudfront-us-east-1.images.arcpublishing.com/cmg/7QOJU3BNCJERBNKJC5LWTBYFLU.png)
