AQUACULTURE
The growing of plants and animals on land for food and other products is
agriculture. Raising animals and plants in the water is aquaculture. Practised since
ancient times in many parts of the world, aquaculture embraces such diverse
activities as the Chinese tradition of growing carp in ponds, the harvesting and
processing of seaweed in Iceland and the artificial culture of pearls - a Japanese
invention. Aquaculture can take place in still water or running water, fresh water or
salt water. The practice of aquaculture has been growing rapidly. Experts have
projected a five-fold increase in harvests during the final quarter of the 20th century.
In the 1970s, Asia accounted for approximately 85% of world production in the field.
Aquaculture is regarded as one possible solution to the world's food supply
problems. The quantity of tillable land is limited and shrinking everywhere. But two
thirds of the globe is covered with water, and the supply of food animals and plants
that may be grown there is almost limitless. In contrast to agriculture, which is
practised on the land's surface only, aquaculture is three-dimensional. Within the
same vertical region, several different crops can be grown at once - near the water
surface, on the bottom, and in the area between. Multiple cropping of this kind,
called polyculture, represents an efficient use of labour, materials and energy.
Moreover, aquaculture is less affected by climatic change - droughts, floods, and
extremes of heat and cold - than is agriculture.
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