Introduced species and aquaculture

The yield from global capture fisheries is the current main sources of seafood for human consumption but has reached a plateau since 1990, and is not expected to have any further significant growth. Aquaculture contributions have increased significantly since 1970 and now account for more than 32.3% of all fish consumed worldwide in 2004 (FAO, 2006). From 1950 to 2004, a total of 442 aquatic species have been cultured at least one time in the world (FAO 2006). In 2003, of these species, 314 had production of one tonne or more. Problems associated with the culture of local species led culturists in many regions of the world to seek related non-indigenous species as alternatives (Stickney, 2001). Aquaculture, then, has become the main cause of the introduction of non-indigenous species, accounting for 38.7% of introduced species recorded in the Food and Agriculture Organization (FAO) database (Garibaldi and Bartley 1998). The practice of culturing non-indigenous species has existed for many years to take advantage of existing markets, as well as available technology and resources. Almost 10% of global aquaculture production came from introduced species (Garibaldi and Bartley 1998). The pressure to culture non-indigenous species has increased, given expanding aquaculture production and increasing demand for diversified seafood from consumers. Aquaculture farms in the United States currently produce more than 100 different species of aquatic plants and animals; most major aquatic species cultured in the U.S. are not native to their farm sites (Naylor et al., 2001). Non-indigenous species have been introduced for farming in particular regions because of the immediate social and economic benefits. Some non-indigenous species, however, have quickly adapted to their new environment, have become established, and now compete with indigenous species for limited habitats. Biological invasions are recognized as serious threats to marine biodiversity and ecosystem structure and function (Frisch and Murray, 2002). In addition, introduction of non-indigenous species for aquaculture has resulted in numerous unintentional introductions of pathogens, parasites, and pest species (Galil, 2000). This presentation will review and provide several cases for the significance of introduced species to total aquaculture production. The culture of marine shrimp will be used as an example to explain the impacts on surrounding environments in both physical and biological aspects. To keep the contribution of introduced species in aquaculture a positive one, certain measures must be developed to avoid any negative impacts. Thus, mitigation strategies and monitoring capabilities for introduced species are very important.