Richard and Rhoda Goldman Conference Room
If aquaculture is to play a responsible role in the future of seafood here at home, we must ensure that the "blue revolution" in ocean fish farming does not cause harm to the oceans and the marine life they support. The ratio of wild fisheries inputs to farmed fish output has fallen to 0.63 for the aquaculture sector as a whole but remains as high as 5.0 for Atlantic salmon.
Continued growth in farmed salmon production worldwide--combined with emerging growth in the production of other lucrative farmed finfish species such as bluefin tuna, cod, and halibut--threatens marine ecosystems and heightens the need for sustainable solutions to farming practices. The debate over "whither farmed salmon" remains widely polarized, with environmental groups calling for the complete elimination of marine aquaculture or a move to land-based systems that are economically unviable under current market conditions.
Global aquaculture production is growing rapidly, with production more than doubling in weight and by value from 1989 to 1998. With many capture fisheries catches peaking, scientists, governments, and international organizations all point to aquaculture as the most important means to increase global fish supplies.
The aquaculture industry in the United States, which is dominated by freshwater catfish (Ictalurus punctatus) production, generates about one billion dollars each year. Marine aquaculture comprises roughly one-third of U.S. production by weight, and despite rapid increases in salmon and clam production, growth of U.S. marine aquaculture has been slow on average. Efforts to develop marine aquaculture in the open ocean could catalyze future growth.
Aquaculture has a number of economic and other benefits. But if it is done without adequate environmental safeguards it can cause environmental degredation. The main environmental effects of marine aquaculture can be divided into the following five categories:
1) Biological Pollution: Fish that escape from aquaculture facilities may harm wild fish populations through competition and interbreeding, or by spreading diseases and parasites. Escaped farmed Atlantic salmon (Salmo salar) are a particular problem, and may threaten endangered wild Atlantic salmon in Maine. In the future, farming transgenic, or genetically modified, fish may exacerbate concerns about biological pollution.
2) Fish for Fish Feeds: Some types of aquaculture use large quantities of wild-caught fish as feed ingredients, and thus indirectly affect marine ecosystems thousands of miles from fish farms.
3) Organic Pollution and Eutrophication: Some aquaculture systems contribute to nutrient loading through discharges of fish wastes and uneaten feed. Compared to the largest U.S. sources of nutrient pollution, aquaculture's contribution is small, but it can be locally significant.
4) Chemical Pollution: A variety of approved chemicals are used in aquaculture, including antibiotics and pesticides. Chemical use in U.S. aquaculture is low compared to use in terrestrial agriculture, but antibiotic resistance and harm to nontarget species are concerns.
5) Habitat Modification: Marine aquaculture spreads over 26,000 marine hectares, or roughly 100 square miles. Some facilities attract marine predators, and can harm them through accidental entanglement or intentional harassment techniques.
A number of technologies and practices are available to prevent or mitigate these environmental problems. Options to make U.S. aquaculture environmentally sustainable include:
Rosamond (Roz) Naylor is the William Wrigley Professor, Emerita, of Global Environmental Policy in the Doerr School of Sustainability; and founding Director of the Center on Food Security and the Environment (FSE) at Stanford University. Her research focuses on policies and practices to improve global food security and protect the environment on land and at sea. She has been involved in numerous field-level research projects around the world with her students and has published widely on issues related to global food systems, food policy, and aquaculture. She is the co-chair of The Blue Food Assessment, an international initiative aimed at providing a comprehensive scientific evaluation of the sustainability, nutrition, equity, and justice dimensions of aquatic foods cultured and captured in freshwater and marine environments within the global food system. She is a Member of the National Academy of Sciences, a Fellow of the American Association for the Advancement of Science (AAAS), Fellow of the Ecological Society of America (ESA), a Pew Marine Fellow, and a Leopold Leadership Fellow. She is also the Chair of the Board of Directors for the Aspen Global Change Institute and a member of the Scientific Advisory Committee for Oceana. At Stanford, she teaches courses on The World Food Economy, Human Society and Environmental Change, and Food and Security.
The Yaqui Valley, in Sonora, Mexico is a region of rapid demographic, economic, and ecological change in both upland and coastal areas. Situated on the west coast of mainland Mexico on the Gulf of California, the Valley currently comprises 225,000 has of irrigated wheat-based agriculture: recently adding aquaculture to its landscape. It is the birthplace of the Green Revolution for wheat and one of Mexico's most productive breadbaskets.