Transgenic fish: a boon or threat?

Abstract

Erik Stokstad's article “Engineered fish: friend or foe of the environment?” (News Focus, 13 Sept., p. [1797][1]) entertains the premise that the culture of transgenic fish, which grow two to six times faster than conventional fish, “might alleviate pressure on wild stocks.” Two key points not addressed by Stokstad challenge this premise. First, the culture of carnivorous species, such as salmon and trout, already represents a net drain on wild fish populations. Over 2 kg of wild fish are required to produce 1 kg of aquacultured conventional carnivorous fish ([1][2]). In North America and Europe, fish are usually reared in high densities and therefore rely completely on manufactured feeds for sustenance. Manufactured feeds for carnivorous species are typically composed of 35 to 50% fish meal and up to 20% fish oil ([1][2]). The accelerated growth rate of transgenic fish will necessitate an enormous increase in the usage of feeds and their constituent marine feedstuffs. Fish meal and fish oil are typically made from menhaden and anchoveta harvested from the wild. As these species are already being exploited near their maximum sustainable levels ([2][3]), using more of them to create even more feed for transgenic fish can hardly be considered an easing of pressure. Second, on the basis of the Law of Conservation of Matter, increased feed inputs will result in more outputs of waste in aquaculture effluents [e.g., ([3][4])]. Reclamation of aquaculture waste is already problematic. In net-pen culture, for example, untreated wastes are expelled directly into the surrounding waters and commonly cause local eutrophication, buildup in sediments of feed-borne antibiotics, and benthic anoxia ([4][5]). Although the degree of these impacts depends on husbandry practices and the hydrodynamics of the site, the potential for serious environmental damage will increase with the increased feed usage required by transgenic fish culture. Add the potential effects of interbreeding between transgenic escapees and wild fish discussed by Stokstad, and transgenic fish culture appears more threat than boon to the wild fishery. 1. [↵][6]1. R. L. Naylor 2. et al. , Nature 405, 1917 (2000). [OpenUrl][7] 2. [↵][8]Food and Agricultural Organization (FAO), The State of World Fisheries and Aquaculture 2000 (FAO, Rome, 2000). 3. [↵][9]1. H. Ackefors, 2. M. Enell , Ambio 19, 28 (1990). [OpenUrl][10] 4. [↵][11]British Columbia Environmental Assessment Office, Salmon Aquaculture Review , vol. 3 (British Columbia Environmental Assessment Office, Victoria, Canada, 1997). [1]: /lookup/doi/10.1126/science.297.5588.1797 [2]: #ref-1 [3]: #ref-2 [4]: #ref-3 [5]: #ref-4 [6]: #xref-ref-1-1 View reference 1 in text [7]: {openurl}?query=rft.jtitle%253DNature%26rft.volume%253D405%26rft.spage%253D1917%26rft.atitle%253DNATURE%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [8]: #xref-ref-2-1 View reference 2 in text [9]: #xref-ref-3-1 View reference 3 in text [10]: {openurl}?query=rft.jtitle%253DAmbio%26rft.volume%253D19%26rft.spage%253D28%26rft.atitle%253DAMBIO%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [11]: #xref-ref-4-1 View reference 4 in text