Americans eat a lot of seafood — so much that the US imports $24 billion worth of seafood each year. The University of New Hampshire has developed a new, sustainable commercial aquaculture fishing system, and received federal funding this summer to take the project nation-wide.
A five-minute boat ride from the coast of New Castle near Fort Constitution, two rectangular pens float on the ocean’s surface, covered with large netting. A narrow walkway surrounds them.
Inside the pens live steelhead trout — called rainbow trout before they move from freshwater to seawater — along with mussels, kelp, and seaweed. It’s here that around 2400 trout will live and grow from November through June, for harvesting in July and August.
“They are a little small right now because our winter was the coldest I've seen in 20 years,” Michael Chambers, a research professor at the Center of Sustainable Seafood Systems at UNH said. “We had periods where it was just barely above freezing.”
The whole contraption is called the AquaFort, so named for Fort Constitution nearby.
Unlike traditional commercial fishing, which can cause habitat damage, harm endangered species, and lead to overfishing, aquaculture involves farming plants and animals in aquatic environments in a way that is protective of local ecosystems while producing commercial seafood.
In the AquaFort, steelhead trout waste is processed by the other species in the pen. Sugar kelp and dulse seaweed filter ammonia and mussels take up solid excrements. In cruder terms, they help deal with the fish pee and poop, like a biological sewage system.
“The goal is to grow out this area so that we can have larger amounts of of shellfish, including mussels, oysters and sea scallops, in addition to seaweeds like sugar kelp,” said David Fredriksson, a professor of ocean engineering and the director of the Center for Sustainable Seafood systems at UNH.
The team has buoys to collect environmental data downstream of the pens so they can monitor the AquaFort’s environmental impact.
“And we typically see nothing,” Fredriksson said. “And so our interactions with the environment are almost negligible.”
The team raises about 20,000 pounds of fish a year that is processed and distributed to local markets along the seacoast. Any profits made are returned to the research operation at UNH.
Chambers said that New England used to be a hub of the US seafood industry.
“Now it only produces maybe 25% of seafood for the U.S. marketplace,” he said. “So it’s very important that we start becoming more competitive and growing our own seafood here.”
This method created at UNH has been so successful that the team has received federal funding from the National Oceanic and Atmospheric Administration and the National Science Foundation to take the AquaFort method beyond New England and all over the country, adapting to local species in Puerto Rico, Alabama, California, and more.
They’re even bringing their work outside the US, too. Fredriksson and Chambers went to the Bahamas earlier this year to meet with community leaders, fishing organizations, and local fishermen and their families.
“It was just absolutely amazing the interest that they had for small scale, community based operations like this,” Fredriksson said. “So it would supplement the capture fisheries with responsible farm fish.”
Because the AquaFort is relatively self-sustaining (aside for the occasional maintenance and ecological monitoring checks), once the trout are placed in the pens in November, the team’s role is mostly to feed the trout until harvesting time.
The fish food looks like dime-sized pellets of dog food, and it’s largely made up of wheat and poultry meal. In other words, the fish eat chicken-kibble.
Chambers said that the steelhead trout are schooling fish, which means they prefer to be living in a pack and the size of the pen works for them. Prior research indicates that the fish don’t do as well in low-density spaces.
“They feel more comfortable,” Chambers said. “Initially when they're small and you throw feed in, the fish over there may not see it. But these fish see it, and when they react, then they're able to react.”
Soon, these fish will be ready for harvesting.
One of the pillars of the AquaFort program is a focus on distributing to local retailers to reduce its carbon footprint.
In the summer the UNH team takes freshly harvested fish to local fish markets, such as Seaport Fish in Rye and Sanders Fish Market in Portsmouth. They also bring the fish to local restaurants like Row 34 in Portsmouth.
Any spare fish is processed and smoked at Boston Smoked Fish Company, which can extend the shelf life of the fish to about a year. They also tin the fish through Island Creek Oysters in Massachusetts.
Rich Pettigrew, owner of Seaport Fish in Rye, one of the local retailers who sells the steelhead trout, said that in the run-up to trout season, his customers specifically ask for the fish from UNH.
“Especially with the rising seafood prices, the global demand on seafood, it's having a nice local product right here,” Pettigrew said. “[They’re] able to keep the cost down as much as you can because there's no real transportation.”
Pettigrew purchases whole fish and breaks it down into fresh filets, which are popular with customers. He also sells the steelhead trout to restaurants and stocks some of the smoked fish packets.
“Aquaculture is going to be the future of the seafood industry,” said Pettigrew. “I mean, without it, you wouldn't be able to supply all the seafood that we have. So you absolutely have to have it.”
