CHAPTER 25 BEYOND THE MONOSPECIFIC APPROACH TO ANIMAL AQUACULTURE — THE LIGHT OF INTEGRATED MULTI-TROPHIC AQUACULTURE THIERRY CHOPIN, PH.D. 1 , CHARLES YARISH, PH.D. 2 , AND GLYN SHARP, M.SC. 3 1 University of New Brunswick, Centre for Coastal Studies and Aquaculture, Centre for Environmental and Molecular Algal Research, Department of Biology, P.O. Box 5050, Saint John, New Brunswick, E2L 4L5, Canada (E-mail:: tchopin@unbsj.ca) 2 University of Connecticut, Department of Ecology and Evolutionary Biology, University Place, Stamford, Connecticut, 06901-2315, USA 3 Department of Fisheries and Oceans, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia, B2Y 4A2, Canada Abstract: The focus of present-day aquaculture is typically monospecific animal culture. Even the development of ‘‘alternative’’ species for aquaculture usually refers to alternative species of fish or shellfish. However, although introducing another species of fish or shellfish may have short-term benefits, rarely does it balance energetically and ecologi- cally in the long term. What is needed is appropriate proportions of different co- cultured organisms, performing different processes throughout the day and seasonally. Other than in Asia, the fundamental role and the contribution of seaweeds in coastal waters have frequently been either ignored or misunderstood. Seaweeds are rarely factored into modeling equations of coastal systems. At a time when nutrification of coastal waters is becoming a pressing issue worldwide and the contribution of the inorganic output of aquaculture to regional nutrient loading is becoming more widely recognized, integrating seaweeds, which act as biological nutrient scrubbers, into fish or shellfish aquaculture is a promising, balanced-ecosystem approach. Integrating seaweeds into aquaculture systems provides bioremediation capability, mutual bene- fits to the co-cultured organisms, and economic diversification of the industry by producing another value-added marine crop. We discuss these concepts and illustrate the benefits of integrated multi-trophic aquaculture (IMTA) using projects that we are conducting in New England, USA, in which the culture of the red alga Porphyra (nori) is integrated with salmonid culture, and in the Maritime Provinces, Canada, in which open-water aquaculture of Chondrus crispus (Irish moss) is conducted in proximity to mussel and oyster aquaculture operations. The aquaculture industry recognizes its Theresa M. Bert (ed.), Ecological and Genetic Implications of Aquaculture Activities, 447–458. ß 2007 Springer. 447