More fish than free-range meat in future diet

Posted: 13 November 2000

Fish farming may overtake cattle ranching as a food source by the end of this decade, according to the Worldwatch Institute. Aquacultural output grew from 13 million tons of fish produced in 1990 to 31 million tons in 1998. Increasing at 11 per cent a year over the past decade, it is the fastest growing sector of the world food economy.

This record aquacultural growth is signalling a basic shift in our diet. During the 20th century, the world relied heavily on two natural systems - oceanic fisheries and rangelands - to satisfy a growing demand for animal protein, but that era is ending as both systems are reaching their productive limits.

Between 1950 and 1990, beef production, four-fifths of it from rangelands, nearly tripled, climbing from 19 million to 53 million tons before plateauing. Meanwhile, the oceanic fish catch grew from 19 million to 86 million tons, more than quadrupling, before levelling off. Since 1990, there has been little growth in either beef production or the oceanic fish catch.

Additional production of beef or seafood now depends on placing more cattle in feedlots or more fish in ponds. At this point, the efficiency with which cattle and fish convert grain into protein begins to reshape production trends and thus our diets. Cattle require some seven kilograms of grain to add one kilogram of live weight, whereas fish can add a kilogram of live weight with less than two kilograms of grain.

Water scarcity is also a matter of concern since it takes 1,000 tons of water to produce 1 ton of grain. But the fish farming advantage in the efficiency of grain conversion translates into a comparable advantage in water efficiency as well, even when the relatively small amount of water for fish ponds is included. In a world of land and water scarcity, the advantage of fish ponds over feedlots in producing low-cost animal protein is clear.

China in the lead

In contrast to meat production, which is concentrated in industrial countries, some 85 per cent of fish farming is in developing countries. China, where fish farming began more than 3,000 years ago, accounted for 21 million tons of the 31 million tons of world aquacultural output in 1998. India is a distant second with 2 million tons. Other developing countries with thriving aquacultural sectors include Bangladesh, Indonesia, and Thailand.

Among industrial countries, Japan, the United States, and Norway are the leaders. Japan's output of 800,000 tons consists of high-value species, such as scallops, oysters, and yellowtail. The US output of 450,000 tons is mostly catfish. Norway's 400,000 tons is mostly salmon.

With overfishing now commonplace, developing countries are turning to fish farming to satisfy their growing appetite for seafood largely because the oceanic option is not available to them as it was earlier to industrial countries. For example, as population pressure on the land intensified in Japan over time, it turned to the oceans for its animal protein, using scarce land for rice. Today Japan's 125 million people consume some 10 million tons of seafood each year. If China's 1.25 billion were to eat seafood at the same rate, they would need 100 million tons-the global fish catch.

In China, fish are produced primarily in ponds, lakes, reservoirs, and rice paddies. Some 5 million hectares of land are devoted exclusively to fish farming, much of it in carp polyculture using four types of carp that feed at different levels of the food chain. In addition, 1.7 million hectares of rice land is used to produce rice and fish together.

Most of China's aquaculture is integrated with agriculture, enabling farmers to use agricultural wastes, such as pig manure, to fertilize ponds, thus stimulating the growth of plankton. As land and water become scarce, China's fish farmers are intensifying production by feeding more grain concentrates to raise pond productivity. Between 1990 and 1996, China's farmers raised the annual pond yield per hectare from 2.4 tons of fish to 4.1 tons.

A world that is reaching the limits with both oceanic fisheries and rangelands while adding 80 million people each year needs efficient new sources of animal protein. Herbivorous species of fish, such as carp grown in polycultures, carp grown in combination with rice, or catfish grown in ponds, offer a highly efficient way of expanding animal protein supplies in a protein-hungry world.

Fish farming is not a solution to the world food problem, but as China has demonstrated, it does offer a potential source of low-cost animal protein for lower income populations. The forces that have made aquaculture the world's fastest growing source of animal protein over the last decade are likely to make it the fastest growing source during this decade as well.

See the Worldwatch report.