Improved fish husbandry is another project focus, and that begins in the hatchery. We work with Great Bay Aquaculture in Portsmouth, N.H., to refine the science and business of incubating, hatching, and rearing fingerlings.

To promote healthy fish, Great Bay carefully screens wild brood stock, disinfects eggs, and minimizes hatchery stress wherever possible. Since young cod—a current focus for UNH—are only willing to eat live feed, Great Bay also grows microscopic rotifers and brine shrimp for the fish to eat. These “probiotics” may promote fish health. To directly combat disease, fish are vaccinated at the hatchery, a practice that reduces the need for antibiotics in offshore pens. To date, we have not used antibiotics at our offshore demonstration site.

Once fish are stocked offshore, we gather information on their behavior to help advance fish husbandry techniques. Alongside firsthand diver observations, we use video cameras to stream real-time footage and ultrasonic transmitters and underwater hydrophones to track fine-scale movements of the fish. A new current meter is helping to correlate fish movements to environmental conditions. Such information informs how often, how much and when to feed cod; it could also inform future cage design to promote fish health, and future farm site selection.

The transmission of disease or parasites from fish farms to wild fish populations is a scientifically controversial issue. While we have not observed this during our research with cod, halibut, flounder, and haddock, we are working to develop environmentally-friendly antifouling methods to reduce the growth on cages of marine organisms that may serve as a reservoir for parasites.