N.H. fishermen have been actively involved in raising steelhead trout just off the coast from Fort Constitution at the mouth of the Piscataqua River for the past two years. But the trout aren't the only living organism growing in the pens -- sugar kelp and blue mussels, both species that occur naturally in the Gulf of Maine, have been growing on the mooring lines for the trout nets. N.H. Sea Grant marine aquaculture specialist Michael Chambers said the kelp and mussels both help extract nutrients from the river and from the trout in the underwater nets.
Tiny blue mussels, called “spat,” were collected from the wild and seeded on 4 m lines suspended around the trout cages. As filter feeders, they remove particulate matter and nutrients from the water surrounding the cages and coming in from the river. The mussels were raised to 40-60 mm before they were stocked in modified lobster pots by the seven N.H. fishermen that assist with the daily care and maintenance of the steelhead trout and their cages.
Last October, the fishermen placed the mussels in the lobster pots and moved them to deeper offshore waters to grow during the winter. After six months at sea, the mussels can be harvested and sold to local markets, providing additional revenue to the fishermen who are helping out with this project.