Open ocean aquaculture can offer both economic and environmental advantages over other culture methods. O ceanographic conditions in large areas of many countries, Canada and the United States included, are unsuitable for surface pens, making submerge options an interesting consideration for many farmers. The heavy wave s at exposed sites can damage pens that are not designed for this level of energy causing excessive repairs costs, stress to fish, and escapes.
The development of submerged pen systems has the potential to enhance the feasibility and range of offshore production by keeping infrastructure out of surface waters and away from damaging wave energy.
Submerged systems can offer further benefits by accessing sites that can support higher stocking densities,
keeping
fish out of extreme temperatures, and away from parasites near the surface. Submerged pens are being used successfully to grow several species around the world.
Salmonids and other physostomal species (fish with “open”
swim bladders) , cannot be maintained without access to air for extended periods. They require an air-water interface to gulp air and maintain an inflated swim bladder and neutral buoyancy. When held for too long without surface access, they start to modify their swimming to compensate negative buoyancy, and eventually start to experience stress and can suffer from injury from bumping into or rubbing on the pen net. FCR will increase as fish swim less efficiently and suffer injury, and mortality can result from the stress.
Both operational and engineering solutions are being developed to make submersible pens compatible for salmonids . Periodic emergence and submerged air reservoirs are two solutions being considered for successful production.
This talk will review the benefits of farming salmon in submerged pens, with a focus on the US and Canadian east coast and explore some of the solutions being considered for swim bladder inflation.