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NEWS FROM THE WORLDWATCH INSTITUTE
From the Office of the Chairman
Worldwatch Issue Alert
Alert 2000 - 9
For Immediate Release
October 3, 2000
FISH FARMING MAY SOON OVERTAKE CATTLE RANCHING AS A FOOD
SOURCE
Lester R. Brown
Aquacultural output, growing at 11
percent a year over the past decade, is
the fastest growing sector of the
world food economy. Climbing from 13 million
tons of fish produced in 1990
to 31 million tons in 1998, fish farming is poised
to overtake cattle
ranching as a food source by the end of this decade.
This record aquacultural growth is signaling a basic shift in our diet. Over
the last 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 leveling 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
7 kilograms of grain to add 1 kilogram
of live weight, whereas fish can add
a kilogram of live weight with less than 2
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.
In contrast to meat production, which is concentrated in
industrial
countries, some 85 percent 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 U.S. 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.
Although at least 220 species of fin fish, shellfish,
and crustaceans are
farmed commercially, a dozen or so dominate world
output. Among the fin fish,
five species of carp--all widely grown in
China--lead the way with a combined
output of some 11 million tons in 1998,
more than a third of world aquacultural
output. Among shellfish, the
Pacific cupped oyster, at 3.4 million tons
(including shell), dominates,
followed by the Yesso scallop and the blue mussel.
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. In
addition, 1.7 million hectares of
rice land is used to produce rice and
fish together.
Over time, China has evolved a fish
polyculture using four types of carp
that feed at different levels of the
food chain. Silver carp and bighead carp
are filter feeders, feeding on
phytoplankton and zooplankton, respectively. The
grass carp, as its name
implies, feeds largely on vegetation, while the common
carp is a bottom
feeder, living on detritus that settles to the bottom. 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. Fish polyculture, which typically
boosts the fish yield
per hectare over that of monocultures by at least
half, also dominates fish
farming in India.
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.
In the United States, catfish,
which require only 1.6 kilograms of feed to
gain 1 kilogram of live weight
is the leading aquacultural product. With U.S.
catfish production last year
at roughly 600 million pounds (270,000 tons), or
more than 2 pounds for
each American, U.S. consumption of catfish exceeded that
of lamb and
mutton. U.S. catfish production is concentrated in four states:
Mississippi, Louisiana, Alabama, and Arkansas. Mississippi, with some 174
square
miles (45,000 hectares) of catfish ponds and easily 60 percent of
U.S. output,
is the catfish capital of the world.
Among the aquatic species that are widely farmed, two especially wreak
extensive environmental havoc--salmon, with production of 700,000 tons per
year,
and shrimp at 1,100,000 tons per year. Salmon are grown mostly in
industrial
countries, principally in Norway, for consumption in those
countries. Shrimp, by
contrast, are grown largely in developing countries,
importantly Thailand,
Ecuador, and Indonesia, for export to more affluent
societies.
Salmon, a carnivorous fish, are fed a diet
consisting primarily of fishmeal
that is typically made from anchovies,
herring, or the remnants of fish
processing. In stark contrast to the
production of herbivorous species, such as
carp and catfish, which lighten
the pressure on oceanic fisheries, salmon
production actually intensifies
pressure because it requires up to 5 tons of
landed fish for each ton of
salmon produced.
Another concern is that if farmed
salmon, which are bred for fast growth and
not for survival in the wild,
escape because of damage to the pens by storms or
attacks by predators,
such as harbor seals, they can breed with wild salmon,
weakening the
latter's capacity to survive. Fish grown in offshore cages or
pens, as
salmon frequently are, also concentrate large quantities of waste,
which
itself presents a management problem. For example, the waste produced by
farmed salmon in Norway is roughly equal to the sewage produced by Norway's
4
million people.
Shrimp are often produced by
clearing coastal mangrove forests which protect
coastlines and serve as
nurseries for local fish. Mangrove destruction can cause
a decline of local
fisheries that will actually exceed the gains from shrimp
production,
leading to a net protein loss. In addition, because shrimp rations
are also
high in fishmeal, shrimp, like salmon, put additional pressure on
oceanic
fisheries.
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.
FOR ADDITIONAL DATA: www.worldwatch.org/alerts/indexia.html
COPYRIGHT: 2000 Worldwatch Institute
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