InitiativesNewsMarketsScienceGet Involved

Read Our Newsletters For the latest marine science and other ocean news, subscribe to Ocean Update, Marine Science Review and our other free newsletters.

Marine Aquaculture

Marine aquaculture or mariculture is the cultivation of marine life for human consumption or use-farming and gardening of the sea. Although the most common purpose of mariculture is to produce marketable food, there are other possible uses: e.g. to strip sewage water of its toxic contaminants and nutrients, to produce substances for food processing or industrial use, and to produce medicines and medical products.

The Issue

  • Aquaculture in coastal waters is becoming more common throughout the world. Because of unsustainable practices and poor coastal management, aquaculture has exceeded environmental limits in some regions. There is a great potential for "sustainable" aquaculture that does not damage and may even enhance coastal ecosystems, but it has not yet been realized.
  • Industrial scale and congested aquaculture facilities often create pollution leading to severe habitat destruction, The pollution comes from feces and food wastes flushed into the surrounding environment,
  • The siting of culture facilities often does not take into consideration their interaction with the surrounding environment. They are often placed in inappropriate locations where environmental damage and/or aesthetic problems are maximized.
  • Marine aquaculture often has resulted in the introduction of non-native species. Sometimes such species are purposely released into the local environment to grow, reproduce, and be harvested as has been done along the west coast of the U.S. with the non-native Japanese oyster and Manila clam. Other species escape from more confined culture facilities. Some species associated with imported aquaculture species are unknowingly introduced. For example, the oyster drill, a species of anemone, and Spartina marsh grass were all accidentally transferred into Pacific coast waters with oysters imported for aquaculture.
  • The use of hatcheries to augment wild populations of popular fisheries species may in the end interfere with those wild populations by interbreeding with them and thereby altering their genetics and survival rates.
  • Aquaculture might also endanger native sealife by exposing it to diseases that run rampant in the overcrowded and stressful conditions of aquaculture facilities. The use of antibiotics to reduce diseases in the culture systems only adds to the potential environmental problems in natural waters. The full effects of antibiotics on native sealife are as yet unknown.
  • Some coastal aquaculture practices permanency alter natural habitats. For example, shrimp ponds are often constructed by cutting down mangrove habitats along tropical coastlines. This activity has been responsible for the loss of two-thirds of mangrove forests in the Philippines, more than half in Thailand, and more than a fourth in Ecuador.
  • Aquaculture often uses feed derived from fish caught specifically for fish-meal production. Using wild fish to grow farmed fish defeats dhe whole purpose of "feeding the world" more efficiently with aquaculture. There is, however, a concerted research effort to develop vegetable protein feeds that are efficently utilized.
  • While there are attempts by the aquaculture industry to retrofit some of their technologies to make them individually more sustainable and compatible with the ecosystem, there has been no concerted government or industry effort to evaluate or manage aquaculture to make it regionally sustainable or to integrate it into the ecology and sustainable management of the coastal zone.

The Causes

  • Although aquaculture is often considered an important contribution to feeding growing human populations, marine aquaculture focuses upon luxury markets which maximize profits.
  • Marine aquaculture is often touted as a replacement for fisheries lost to overfishing, but in many cases it may, in fact, negatively impact wild fish populations. For example, in New England money is being requested for developing the aquaculture industry without always considering the impact on the local habitats upon which the recovery of wild fisheries depends.
  • There is a tendency to over-develop a single type of coastal aquaculture in a region-e.g. salmon in western North America, shrimp in certain tropical countries. The intensive cultivation of a single species over a large area has been shown to compound environmental problems, whereas an appropriate mixture of species can minimize environmental problems.
  • Regulations on coastal aquaculture are often ill-conceived and may present unnecessary difficulties for the aquaculture industry as well as fail to protect the environment.
  • Innovative aquaculture has not been well supported, so ecologically sound alternatives to destructive aquaculture are not fully developed or readily available on a commercial scale.

The Context

  • In the U.S., several kinds of shellfish are cultivated, usually in estuary settings. Oysters, mussels, clams and other molluscs are the most common, and some shrimp mariculture occurs on the Gulf coast. With shrimp stealing the limelight because of the environmental havoc their culture has wrought world wide, not enough attention has been given to the other shellfish that can be grown sustainably.
  • Marine finfish aquaculture has been less common, except for hatcheries which are commonly operated to enhance stocks of wild fisheries. But now salmon are widely cultivated and a few other fish are being developed, in particular the red drum, which grows on the Gulf coast. Salmon are reared extensively in the northwest, with the concomitant environmental controversy, and are becoming more common in the northeast, where the jury on environmental impacts is still out.
  • The potential for marine aquaculture to provide a variety of foods and services while maintaining healthy ecosystems has been the subject of many research projects and academic conferences. Research on sustainable matine aquaculture often incorporates "polyculture" systems, in which several different species are grown in the same system-some marketable, some providing a service, such as cleaning the water.
  • The use of aquaculture in protecting or restoring coastal ecosystems has been rare but shows promise, e.g., to restore saltmarsh plants and seagrasses and to establish wetlands for filtering sewage water.

Further Reading

Goldburg, R. and T. Triplet. 1997. Murky Waters: Environmental Effects of Aquaculture in the US. Environmental Defense Fund. New York, NY.

National Research Council. 1992. Marine Aquaculture Opportunities for Growth . National Academy Press. Washington, DC.

Pacific Congress on Marine Science and Technology. 1995. Proceeding of the PAGON Conference on Sustainable Aquaculture '95. Honolulu.