Sustainable Aquaculture in the Twenty-First Century

There have been many efforts to create a conceptual framework for understanding and defining sustainable aquaculture. A recent consensus or stakeholder view (Caffey et al., 1998) approached sustainability from three perspectives: environmental, economic, and sociological. Often, stakeholder views are snapshot or present oriented. The multiple variables affecting sustainability and viability are considered from a here-and-now perspective rather than considering the effects that significant change in one or several variables might cause. Aquatic nitrogen loads generated from the sewage effluent of a growing, global human population (15 billion vs. 6 billion people) may prevent the legal discharge of any aquacultural effluents. Much of the intensive aquaculture industry has a highly centralized structure with respect to production and distribution. This centralized development has flourished around energy-rich — at times extravagant — cultures and economies. How will increased costs or shortages of electricity, gasoline, and diesel fuel affect the sustainability or survival of the current production system? Does a large, centralized industry provide more jobs and profit or a better quality of life (per capita) than widely dispersed, small-scale operations producing at local or county levels? Nutrient recycling (converting nitrogen back to protein) through different polyculture systems could be more practical and efficient than controlling or treating the effluents associated with traditional, intensive monoculture practices. Phytoplankton and zooplankton occupy sizable respiratory (oxygen consumption) niches in the production pond environment — and have no market value. Careful selection of suitable filter feeding fish and mollusks for polyculture could open up these niches for the production of species with greater economic value. It might be more desirable to culture channel catfish with paddlefish and some species of freshwater mussel than to face bankruptcy because it has become illegal to discharge effluents from production ponds used for intensive monoculture. Ultimately, sustainability may be the aquaculture industry's ability to adapt on a planet with an ever-increasing human population that continues to consume its limited supply of nonrenewable resources at an alarming rate.