Integration of transgenic fish into aquaculture

Abstract

Abstract Research on genetic manipulations has expanded significantly in the last decade and, most recently, has included the transfer of novel genes into fish. Researchers in numerous laboratories around the world are pursuing the isolation of fish genes, for example, growth hormone and antifreeze protein genes, and the production and evaluation of transgenic fish. The long‐term objective is to insert DNA sequences derived entirely from the host aquacultural species; several research groups are reaching this stage. Most reports to date have involved genes derived from other vertebrates or microorganisms. In some cases, gene transfer experiments have utilized model fish species with shorter generation times than aquacultural species. These preliminary experiments have allowed researchers to tackle the many technical problems of gene transfer until numerous commercially important fish genes are isolated. Cumulatively, reports on transgenic fish have shown evidence for: integration of inserted genes into host chromosomes, although often in a mosaic pattern in the first generation; expression in fish tissues; and germ line transmission. Practical use of transgenic fish in aquaculture awaits the development of cost‐effective protocols for gene transfer on a large scale, facile identification of transgenic individuals within a treated group, and selective breeding for superior phenotypes with respect to both transferred and endogenous genes. Much uncertainty surrounds the question of environmental impacts associated with the accidental escape of transgenic fish from aquaculture operations. Application of recently developed sterilization methods, including chromosomal and hormone manipulations, is proposed as a means of reducing environmental risk. To achieve environmentally and economically sound aquaculture of transgenic fish, future research must focus on careful evaluations of the overall performance of transgenic fish with respect to both ecologically and commercially important traits.