Wednesday, October 24, 2012

Steelhead trout aquaculture: N.H. fishermen now in charge

NHSG recently transferred its day-to-day steelhead trout aquaculture responsibilities over to eight local fishermen.

Every week, one of eight Portsmouth fishermen take responsibility to feed and maintain two sea cages filled with steelhead trout and blue mussels. The boat loads up with a bag of fish meal at the Judd Gregg Marine Research Complex in New Castle and motors less than five minutes away. The fisherman will stop by the cage either on the way out or in from their commercial fishing grounds to feed the trout that are being raised in two 20' x 20' floating pens located just south of Fort Constitution at the mouth of the Piscataqua River.

It's a different kind of work for traditional fishermen, but it's helping to supplement their income when times get tight. In early December when the fish reach market weight of 3-4 lbs., the fish will be sold to restaurants and markets in Portsmouth, N.H. and Portland, ME., providing profits that go directly to the fishermen during an otherwise slow period of time for them. 

NHSG aquaculture specialist Michael Chambers and UNH professor of zoology Hunt Howell recently organized a two-day program, funded by NHSG and a Saltonstall-Kennedy grant, to teach fishermen the basics of feeding the fish, harvesting techniques, and maintaining the nets.

Howell taught the group how to purse the nets to gather the fish for harvest and store them on ice to make sure the quality remained top-notch for delivery to restaurants and markets in Portsmouth and Portland.

After harvesting the trout in those pens, Chambers taught the fishermen how to clean the net of the biofouling that occurs: in this case, juvenile blue mussels had naturally settled onto the net, adding weight to the net and constricting water flow. 

However, filter feeders like blue mussels can provide a valuable ecological service by removing excess nutrients from the surrounding water, providing the ability to completely offset any nutrients added by the trout living in the pens. So rather than discard these mussels that had settled on the nets, Chambers and aquaculture technician Jessica Cranney showed the fishermen how to remove them from the net and "re-seed" them onto spat line or into a tube sock made of polypropylene to allow them to continue growing. The lines and socks were suspended around the pen platform to allow the mussels to continue to do their very important work. 

Additional research trout that were held in pens under the pier were then transferred to the sea cages in large insulated bins filled sea with water and pumped full of oxygen. 

The fish-filled bins were then transferred via boat and the trout were carefully moved into their new pens at the mouth of the river. 

After this round of fish is harvested, the nets will be pulled out of the water for the winter and work will start back up in the spring. In the meantime, the public will be able to enjoy locally raised steelhead trout in a couple of months, knowing they are also supporting fishermen that live in their community.

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