Walk past a koi or carp pond in a business park, and you don’t typically think of dinner. Yet in much of Asia, small-scale fish ponds supply much of a family’s protein needs.
Meanwhile, in America, fish farming — or aquaculture — usually elicits a neutral or negative response from people. There are good arguments for fish farming. You’ll find some in the July 18, 2011 issue of TIME magazine, which featured a cover story on aquaculture containing well-researched arguments for it. In a country where the majority of food comes from large farms, feedlots, and dairies, it seems odd that farming fish would take so much convincing for the American people. Why do Americans dislike fish farming?
One reason might be the negligible presence aquaculture has in the lives of Americans. North America produces only about two percent of the world’s aquaculture. In China or Thailand, fish ponds and fish farming facilities are everywhere. Many of these farms are small and akin to the backyard vegetable gardens that dot neighborhoods in the American Midwest.
Many of us view fish farming facilities as eyesores and a negative change, but in reality all agriculture changes the landscape; that is the nature of every agriculture system. When we see row crops on the periphery of major cities, we view them positively, even fondly. We create ordinances to maintain green space, and we consider agricultural transformation to be one kind of green space. But the perception of fish farms and agricultural fields is quite different. Yet both farmer’s fields and fish farms result in the same thing — a major change in the natural ecosystem that was made to produce food.
The seafood rating scales produced by the Monterey Bay Aquarium, Blue Ocean Institute, and Marine Stewardship Council are attempts to define sustainable practices for fisheries and aquaculture. These ratings tell us what is a sustainable food product and what is not.
However, simple definitions don’t fully explore the question of sustainability. For example, should we consider wild-caught species of fish to be sustainable, when many fish populations are heavily overexploited? Should we encourage consumers to avoid farmed shrimp, when many shrimp farmers use sophisticated techniques to clean the water, reduce farm effluents, and control diseases?
Obviously, generalized evaluations cannot take into account each system that is currently used to produce seafood. All they can do is summarize large-scale differences.
The issue of sustainability becomes further confused because it is difficult to make accurate and objective comparisons among different agricultural crops. For example, how can we compare traditional agriculture crops, such as wheat, beef, or pork, to aquaculture? In this case, we don’t even have similar rearing systems and therefore similar production means. All of these considerations cloud the issue of what constitutes a sustainable food product.
Life-cycle assessments hold promise as a more objective method to evaluate the sustainability of seafood. A life-cycle assessment documents the total materials and energy used in a production system, including building the farm, growing the crop, and disposing of the waste, as well as marketing, sales and ultimate consumption of the product.
These analyses not only evaluate energy use and material consumption but can also estimate the global warming potential, eutrophication potential, and a number of other environmental metrics of sustainability. Since a life-cycle assessment is quantitative, it can be used to compare widely diverging production systems. For example, shrimp appear comparable to chicken in the energy cost for producing a kilogram of meat and are considerably lower than pork, lamb or beef. They are also considerably lower than most wild seafood crops.
Americans need to know more about how their food is produced and what the most sustainable methods are. While thoughts about whether to eat farmed or wild seafood are in the minds of many of us, most of the time you often cannot even determine the source of seafood you eat at a restaurant or buy at a store. Our purchasing habits and knowledge can drive the aquaculture sector to use more sustainable methods but only when we make informed decisions in the marketplace.
James S. Diana is Director of the Michigan Sea Grant College Program and Professor of Fisheries and Aquaculture at the School of Natural Resources and Environment (SNRE) at University of Michigan. He and his students, including Keith Hayse-Gregson, are studying ecology of fishes as well as aquaculture. They have developed interests in aquaculture’s potential contribution to the global food supply through the understanding of ecologically sensitive aquaculture practices, particularly in developing countries. They also study a variety of natural ecosystems, focusing mainly on native species, particularly pike and muskellunge. Dr. Diana has studied the behavior and ecology of temperate fishes for three decades, working extensively on the behavior and ecology of many temperate fishes, including pike, muskellunge, brown trout, lake sturgeon, yellow perch, largemouth bass, and alewives. Keith Hayse-Gregson is a second-year MS student at SNRE, who recently conducted a study of the environmental impacts of a new freshwater aquaculture cage design in China.