The views are spectacular at the wall break, 25 m deep, San Salvador, Bahamas.
Sustainability of Aquaculture
Thousands of years ago, humans learned how to farm instead of hunting and gathering. Instead of going after the food, we brought the food to us. As we have made a greater impact on the earth, we now have the need to bring other types of food to us. Fisheries have been depleted in areas of the world where they used to be very abundant. During the 1970’s, aquaculture began to pop into the public eye to combat this. But that was not the first time that aquaculture has been used.
Southeast Asians have used a form of aquaculture for over 2000 years (Santis, 1984). This process actually occurred naturally and was only aided by farmers. Rice paddies provide the perfect habitat for fish and other organisms. These fish, in turn, fertilized the crops to produce more yield. Once this was understood, farmers added more fish larvae to also gain a better fish crop.
Seafood used to be viewed as a luxury, but no longer is today. The consumption of seafood has gone up. From 1988 to 1995, the U.S. per capita consumption of salmon increased threefold, from 0.44 pounds to 1.41 pounds (McGinn, 1998). But commercial fishing areas have been depleted. In July 2003’s edition of Time Magazine, scientists estimated that up to 90% of the predator fish have been depleted from some areas of the ocean.
Aquaculture is seen as a way to combat this. A simple explanation of aquaculture is the controlled growth and production of fish in enclosed or controlled areas. Aquaculture, as defined by the Food and Agriculture Organization is: “the farming of aquatic organisms including fish, mollusks, crustaceans and aquatic plants (ABS, 2003).” It really is farming fish. Farming implies some sort of intervention in the growing process to enhance production, such as regular stocking, feeding, protection from predators, and so on. The two characteristics that distinguish aquaculture from capture fisheries production are intervention in the rearing process and ownership of the stock being cultivated (ABS, 2003). Aquaculture is seen as a way to make up for the falling world fish production and be a more efficient producer of protein as well, but these goals come at costs.
Many people may know or understand that growing monoculture agriculture is not the best thing for the land and causes certain environmental problems. These can include erosion, land degradation, and chemical runoff. In the same way, aquaculture can have harmful environmental effects, especially if grown as a monoculture.
Most aquaculture takes place in enclosed areas such as inland ponds or open water pens. The biggest problem with this is waste. A 2 acre salmon farm in the United States can produce as much waste as a town of 10,000 people (Kane, 1993). This causes water problems in and around the area of the farm. Besides fish being poisoned by their own waste, fecal and urinary products, uneaten fish food, and chemicals and antibiotics used to control diseases are also wastes that may result. These can cause significant organic pollution and increased turbidity of the water and the sea floor sediments in the vicinity of the cages. This results in the temporary disappearance of animals and plants that live on or in the seabed (ABS, 2003). Fish waste and other nitrogen effluence also causes a rapid growth of algae. This results in the algae eventually consuming and depleting the water oxygen (Baringa, 1990).
Fish, like humans, become much more susceptible to the spread of disease when packed into a small living environment. To prevent this, chemicals are then added to the water by fish farmers. This may help neutralize some diseases and effects of fish waste, but chemicals leaking to surrounding areas can have harmful effects on the surrounding environment and ecosystems.
Another problem of aquaculture is escaping sea life. Large numbers of sea life can escape container areas, especially in open water pens. Pens must be put in areas with some tide or current to flush the pens with new water, but these areas are more vulnerable to storms and other problems that could cause the pens to break, and when a pen breaks, it can release thousands of invasive sea life. For example, in July of 1996, in Puget Sound, 100,000 salmon escaped when a pen lost a mooring (The Waters, 1997). In 1993, data from the Norwegian Directorate for Nature Management showed that about 20% of fish caught in the wild have escaped from farms (Kane, 1993). But invasive species aren’t the only problem with escaping wildlife. Many of the animals grown in aquaculture are genetically modified.
Even though aquaculture has stated high and noble goals for its purpose, the primary goal, of course, is money. Fish farmers want to make as much money as possible as quickly as possible. To do this, ideal species must have high market value and grow cheaply and rapidly. In order to accomplish this, farmers change the genetic makeup of grown sea animals. Like modifications such as hybrid corn, farmers have engineered sea life to grow, taste, and look ideal for sale and consumption (Kane, 1993).
One example of this is salmon grown through aquaculture. Salmon in captivity, for some reason, produce gray meat. Fish farmers have developed supplements in salmon feed that when added, turn the gray flesh of the captive fish into the eye-pleasing pink of wild salmon (Kane, 1993). Another example is the African native fish called tilapia. Tilapia is the most commonly grown fish and has been genetically altered to grow up to 60% faster than normal tilapia (McGinn, 1998).
Going back to escaping sea life, this genetically altered sea life can have harmful effects on wild species. It has been predicted that genetically “homogenized” and interbred salmon that escape from farms and breed with wild salmon could potentially cause genetic suicide for wild salmon down the road (The Waters, 1997). Altering the genetic makeup of sea life can produce greater yield, but this seems to come at costs of harmful and often unknown consequences, and the health risks to both humans and the natural environment have been heavily debated.
Besides aquaculture causing environmental degradation through its processes, the environment is also destroyed to make areas usable for aquaculture. Many fisheries depend on estuary habitats including salt marsh, tidal freshwater marsh, seagrass, mangroves etc. (MAP, 2004). These areas are prime natural areas for starting aquaculture productions, especially for shrimp aquaculture, which greatly threatens many of these natural coastal areas (MAP, 2004).
For all its harmful effects, aquaculture has accomplished some of its lofty goals. As seafood consumption has increased over the recent decades, aquaculture has taken up much of the slack. Today, 40% of the seafood that people eat is grown in captivity (The Waters, 1997). Farmed seafood has increased enough to flood the world market and decrease the price of seafood, which actually makes commercial fishing less profitable (McGinn, 1998). Worldwide there are now 2 kilograms of fish produced for every 5 kilograms of beef (McGinn, 1998).
The oceanographer Carl Safina previously said, “Aquaculture will do for coastal systems what agriculture did for the prairies of North America. It replaces natural populations of animals and replaces natural habitats (The Waters, 1997).” On its present course, aquaculture is in danger of doing just that, but it doesn’t have to result in this end. Aquaculture could be made sustainable.
What is sustainability? It is the ability to preserve our present economic and environmental conditions for future generations. In 1987, the World Commission on Environment and Development developed a definition that simply reads: “Sustainable development meets the needs of the present without compromising the ability of future generations to meet their own needs.” Even though this vague definition can be interpreted very differently, the point is therefore, that aquaculture needs to find a way to asses and consider every aspect and consequence of its actions. There needs to be a way to work with the environment and make the smallest impact on ecosystems as possible, while still preserving our economic stability.
However, one of the biggest problems with reaching this goal is that in the past, technological research was never aimed at this. “Most previous research has concentrated on making more money and growing cash crops like lobster and salmon instead of looking to feed the masses (Santis, 1984).”
Once again, to find a sustainable manner of aquaculture, we look to Asia. Many times there, beginning centuries ago, Asians grow seafood in polyculture societies, mimicking more their natural environment. Western Culture needs to learn that several kinds of sea life can be raised together, much like a natural system with mussels, seaweeds, bottom-feeding fish, and top-feeding fish together (Kane, 1993). The Asians also figured out how to use wastes in a constructive manner. Human or animal waste that ran off the land fed organisms that fish could feed on. Fish waste was then used to fertilize rice fields, and the ponds were finally cleaned with tea leaves instead of many chemicals (McGinn, 1998). So aquaculture can be combined with agriculture to result in a more sustainable method of production. This results in many types of crops but in a more sustainable method of production, using wastes to recycle as nutrients (Kane, 1993).
Aquaculture has many problems that need to be solved in order to make it more beneficial than harmful. Research and technology need to be devoted into monitoring aquaculture by setting up programs such as environmental impact assessments, standards, emissions trading, zoning and restrictions for water and resource use, and buffer zones. The sustainability of aquaculture needs to be seen as something we need to devote time and money to. But any advances toward sustainability will come only when the public and the scholarly understand the importance of the impact of this process. As aquaculture grows into more and more prominent production in the future, how our seafood is produced needs to become more of an issue to address.
ABS (Australian Bureau of Statistics). “Forestry and Fishing: Aquaculture and the Environment.” http://www.abs.gov.au/Ausstats/abs@.nsf/ Year Book Australia, 2003.
Baringa, Marcia. “Fish, Money, and Science in Puget Sound.” Science. Edition 247. February 9, 1990.
Kane, Hal. “Growing Fish in Fields.” World Watch. September – October Edition, 1993.
MAP (Mangrove Action Project). http://www.earthisland.org/map/index.html. 2004.
McGinn, Anne Platt. “Blue Revolution.” World Watch. March – April Edition, 1998.
Santis, Marie de. “To Hunt or Farm.” Oceans. Edition 17, 1984.
“The Waters.” Audubon. March – April Edition, 1997.
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