Environmentally Sustainable Salmonid Culture

Until very recently most research relating environmental quality and aquaculture was limited to assessment of environmental conditions necessary for culture. Emphasis was placed on dissolved oxygen requirement of the culture fish or the maximum dissolved nitrogen level that could be tolerated without impairment of growth rates or survival. Most attention was directed towards the effect of the environment upon the aquaculture operation, while the converse perspective, the effect of aquaculture upon environmental quality, was largely ignored. The sustainability of aquaculture development and the environmental impacts of aquaculture operations have become a matter of considerable concern for all stakeholders. The development of the aquaculture industry, especially if it is to sustain its current growth, depends on finding ways to increase its environmental, economic and social acceptability. The technique used to culture salmonids throughout the world varies greatly with respect to the water source and means of confining the fish. With the rapid growth of salmonid cage culture over the past decade has come increased examination of this industry segment as a potential pollution source. Aquaculture pollution mainly originates from the physical and chemical characteristics of feed and the applied feeding management. This article reviews the available information on those environmental impacts of salmonid culture and three reportedly environmentally-friendly alternatives; a marine floating bag system; a land-based saltwater flow-through system; and a land-based freshwater recirculating system