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Does aquaculture pollute the environment? Facts vs. fiction

Subtopics Pollution Regulations in the industry Industry investment in environmental concerns Sustainability

Pollution

Aquaculture gear

In order to examine the relationship between aquaculture and the environment, avoiding any kind of generalisation, we need to state clearly:

• Some simple definitions of the structure of the aquaculture sector
• The meaning of "environmental impact".

"Aquaculture is the farming of aquatic organisms, including fish, molluscs, crustaceans and aquatic plants. Farming implies some form of intervention in the rearing process to enhance production, such as regular stocking, feeding, protection from predators, etc" (FAO Definition of Aquaculture).

Aquaculture (For further information on aquaculture techniques see the web site: http://www.aquamedia.org/Production/CultureMethods/default_en.asp) is an economic activity that is complementary to fishing. It can provide a considerable and increasing supply of fish products.

• Freshwater (aquaculture in inland waters)
• Salt waters (marine aquaculture)
• Brackish waters (for example the Italian "vallicoltura")

• Shellfish as is the case with mussel or clam production
• Finfish as is the case with fish production (sea-bass, sea-bream, trout, carp etc.)
• Crustaceans as is the case with lobster and shrimp production

• Extensive breeding: when fry/juvenile species are "sowed" in their natural habitat and they grow up eating exclusively what is already available in their environs. Except for the first step, in which human activities condition the lifecycle of the species, the remaining steps of the technique are completely natural. No additional feed is provided on the farm
• Semi-intensive or semi-extensive breeding: it is an intermediate technique, halfway between extensive and intensive breeding. Man intervenes by integrating natural feeding with some compound feeds (according to the species living on the farm and their biological size from juvenile to adult, appropriate types of feed are distributed in water in order to aid growth). The production of the farm is organised by man, and managed by nature under man's control
• Intensive breeding: when human action affects almost all the activities on the farm. From the early stages of the life cycle to the harvesting of the species, everything is organised, managed and controlled by man. Farmed species eat only selected compound feeds provided by man (distributed in tanks, raceways or cages).

1. From the pollution point of view
2. From the environmental impact point of view

To pollute means to negatively modify the balance of an environmental condition. In other words, pollution is the "undesirable" effect that reduces the quality of the surrounding environment and is produced by a human action.

The concept of environmental impact is a little more complex. It accounts for all the desired and undesired effects produced in a given area by a human action. When speaking about environmental impact we have to consider also the economic and social dimensions in addition to ecological issues.

Pollution

• Loss of transparency
• Acidity modification
• Dissolved oxygen reduction
• Increase of nutrients
• Increase of algae (eutrophication phenomenon)

• Increase of organic substances
• Increase of chemical mixtures
• Other ground alteration

• Introduction of new species
• Genetic modifications caused by cross-breeding between farmed and native species
• Transmission of illnesses to the natural populations
• Increase in predators around the farms

• The construction of the farm (due to building activity and waste material)
• The normal operating activities (from full productive cycle)
• The conclusion of the farm's activity (rehabilitation of the area)

Environmental impact

• Potential pollution
• Amount of employment created
• Added value for the community
• Introduction of a lower-cost product on the market
• Introduction of a "commercial" product on the market
• Dissemination of expertise
• Controversy regarding the use of land (the area in which the farm is located could be used for other purposes)
• Controversy regarding the use of water (professional fishery; drinking water etc.)
• Controversy regarding integration with recreational activities (recreational fishery, eco-tourism etc.)

• In the surrounding environs of the farm and for local communities
• Within the aquaculture sector and in related sectors (feed producers, trade, services, and so on).

For example, the implementation of a semi-intensive farm in a remote area with few employment opportunities could create new jobs in the area and, depending on the size of the farm, also in the hinterland. At the same time the whole chain, from equipment manufacturers to fish dealers in the downstream market could gain benefits.

It should therefore be clear that the relationship between aquaculture and the environment is not a single one, but that different relationships exist depending on the farms (the aquatic environment, the species raised, the biological characteristics of the species, the breeding system) and of course on the way farms comply with legislative norms (For further information about the relationship between aquaculture and the environment please see http://www.fao.org/docrep/003/w7499e/w7499e14.htm or for the impact of marine aquaculture see the MARAQUA final report on the following web site http://www.lifesciences.napier.ac.uk/maraqua/home.htm).

• Value 0 corresponds to "no impact";
• Value 1 corresponds to "low impact"
• Value 2 corresponds to "medium impact";
• Value 3 corresponds to "high impact"

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