Thursday, April 22, 2010


William A. Wurts

Kentucky State University CEP, UK Research and Education Center
P.O. Box 469, Princeton, KY 42445 USA Debates and discussions about sustainable aquaculture commonly address definitions, policy and legislation but rarely encompass culture practices or industry structure. Sustainable practices should integrate social, economic and environmental concerns. The best approaches would not tax environmental carrying capacity, deplete resources or negatively impact sensitive local and regional ecosystems. Ultimately, future sustainable technologies should fully integrate and exploit environmental productivity while minimizing or eliminating the ecological footprint.

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 cultures and economies. Using United States Department of Energy (DOE) estimates, one can project that recent rates of global crude oil consumption will exhaust the proved world reserves in approximately 36 years. How will increased costs or shortages of gasoline, diesel fuel and electricity affect the sustainability or survival of the current production systems? 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 district levels?

Wastes that result from the high stocking densities and heavy feeding rates of intensive aquaculture push the production unit beyond its (biological) environmental carrying capacity. This necessitates the use of energy and mechanization to maintain acceptable water quality. Furthermore, waste nutrients are discharged with water when the production system is drained.

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. 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 production of species with greater economic value. However, rates of plankton removal must be balanced with population growth rates of the plankton communities harvested. Perhaps pond plankton could be mechanically harvested for feed and nutritional supplements and/or biofuels as well.

Sustainability may be the aquaculture industry's ability to adapt on a planet with a human population that is swelling exponentially and continues to consume its limited supply of non-renewable resources at an alarming rate. Will humanity continue to expand mindlessly? Or can we adapt through self-awareness?

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