Sustainability is the buzz word of the Aquaculture industry. The ultimate goal of aquaculture is to create a sustainable industry. In the ideal situation this means aquaculture's impacts on the environment are negligible and the industry can continue to produce at a steady level indefinitely. No one denies that if these goals can be met aquaculture could produce a larger portion of the food required by the growing human population. It is also commonly accepted that the current level of capture fisheries is not sustainable and if it is not reduced the populations of countless marine species will collapse. Faced with these problems the pressure is on the aquaculture industry to create a viable, environmentally stable industry.

Sustainability is not a single technique or practice, however, but encompasses a whole range of techniques and technologies. Sustainable practices vary depending on the species being cultivated and the location of cultivation. A technique that may be sustainable with one species is not necessarily sustainable with another species, or even with the same species at a different location. However, the concepts that lead to sustainability are common in all practices, the first is the need to determine the carrying capacity of the environment the farm is located in, that is, how much the farm can produce sustainably. Once the carrying capacity has been determined, appropriate farming techniques must be selected that have relatively little negative impact on the surrounding environment.

One way to attain a sustainable culture system is to create a small ecosystem, with a variety of species being harvested. This practice is called polyculture; the practice of culturing only a single species is called monoculture. Ideally the populations of the species in a polyculture should be arranged that many of the nutrients introduced into the system are recycled among the organism, thus reducing nutrient waste and pollution. One such example of polyculture is growing seaweed or oysters along with another fish species. The seaweed and oysters act as a filtration system, utilizing the wastes of the fish, which would otherwise be released into the surrounding environment, resulting in nutrient pollution. This increases the efficiency of the system, while minimizing the impact of the farm on the environment.

Many current aquaculture ventures use monoculture practices. The advantage of monoculture is economic, as it results in an initially larger production than polyculture. Monoculture, however, because of reasons explained above is not as sustainable as polyculture. As a result of some of the early monoculture practices many groups claim that in some cases aquaculture has done more harm than good. The shrimp culture industry is a favorite target of critics. Some of these farms, due to mismanagement, have resulted in severe pollution and habitat destruction problems. A popular target of criticism is the destruction of mangrove swamps by shrimp farms in southeast Asia. The true damage from these ventures is recognized and is being addressed but despite the vast quantities of negative publicity shrimp farms are only a small part of the problem. In all, about 10% of the mangrove destruction is attributed to shrimp farming. The Audio clip below explains the effects of shrimp culture industries on the environment.

Audio clip: Shrimp Farming's Impact on Mangrove Forests  Quicktime and Quicktime plugin are required to hear this clip

Environmental destruction is not only devastating to the local wild plant and animal population, but the damage can eventually become so extensive that the region can no longer support any aquaculture industry. The Chinese white shrimp industry in China is an example of how a lack of environmental concern resulted in the collapse of the industry.The Chinese white shrimp industry is currently recoviering but it is commonly accepted that it will never reach past production levels. One of the important lessons that should be learned from the failure of the Chinese white shrimp farming industry is that although the initial capital investment is smaller to create farms highly productive in the short term, the farms often collapse after only several years of operation. Although more expensive initially, environmentally friendly facilities can continue production long after their environmentally unfriendly farms have fallen. The possible stability of the sustainable farms results in increased production and profitability in the long term.

Many current aquaculture ventures are not sustainable for a variety of reasons, the most prominent being a lack of concern for the environment by farmers. Making a environmentally friendly culture program is much more expensive in the short term because it requires extra equipment and results in initially reduced production. Farmers in many developing countries, where the majority of aquaculture is practiced, often take the environmental resources for granted and exploit them to their fullest extent to produce the maximum product possible. Such unmanaged growth can and has resulted in serious environmental damage and the collapse of the farming industry in the region. The Chinese white shrimp industry is an example of what can happen to a farming industry that is not managed in an environmentally friendly and sustainable manner.

The second major reason some aquaculture practices have proven unsustainable is poor site selection. This is also a symptom of farmers viewing the environmental resources only as a means of increasing their financial status. Many times farmers choose to over exploit the available resources beyond their carrying capacity and use ones that shouldn't be used for a short term profit. The first lesson that needs to be learned is that production cannot be sustained at its highest possible levels and that farmers need to stay within sustainable production levels determined by the carrying capacity of the region and species. Such limitations would exclude the development of new farms in areas where they would significantly degrade environmental quality such as mangrove swamps. Proper sites for farms are areas with little biodiversity or ecosystem importance such as salt and mud flats or other ecosystems less sensitive to human intervention.

There are other numerous small changes that aquaculture farmers could implement to increase their chances of creating a sustainable system. One such change is the implementation of settling ponds where wastes and nutrients are collected and filtered out of the water before it is discharged back into the environment. This will help reduce the pollution and eutrophication that affects waters surrounding aquaculture projects. To help minimalize the pollution and environmental impacts ponds should not be overstocked and should not be stocked with youngsters caught from the wild, but from youngsters hatched in hatching tanks. The chemical additives and nutrients used also have to be closely monitored and controlled.

In all creating a sustainable farm is not cheap but with current technology many believe it is possible. The limiting factor is mainly financial and a matter of attitude. As with everything the final decision is ours and the outcome is our responsibility.

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