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A wide variety of animal and plant species are
produced through aquaculture: finfish; shrimp,
prawns and crabs; clams, oysters and mussels; as
well as seaweeds and other aquatic plants.
Aquaculture provides about one third, or 40
million metric tonnes, of the annual world
fisheries production of 120 million metric tonnes.
Half of all aquaculture production is finfish, a
quarter is aquatic plants and the remaining quarter
is made up of crustacea (such as shrimp, prawns,
crabs) and molluscs such as clams, oysters and
mussels.
The most harvested species in recent years has
been the Pacific Oyster (Crassostrea gigas),
which grossed 3.4 million metric tonnes in 1998.
The Pacific Oyster was the number one aquaculture
species in four out of the five years to 1998.
A close second is a freshwater fish, the Silver
Carp (Hypophthalimichthys molitrix) which
contributes more than 3 million metric tonnes per
year to world totals. Silver Carp are grown in
ponds, mainly in Asia, and eat tiny plankton. In
the early 1990s they were the world's leading
aquaculture species, until 1994 when the Pacific
Oyster took over. Given its higher yield of meat
compared to the oyster, it is arguable that the
Silver Carp is still the world's most important
aquaculture species.
Seven out of the ten top species are freshwater
finfish and six of those are carps. The other three
species figuring in the top ten are molluscs.
Carps accounted for nearly half of the 31
million metric tonnes of fish and molluscs produced
by farming in 1998. Molluscs also made a major
contribution (9.1 million mt) while production of
farmed salmon, tilapia and shrimp totaled around 1
million metric tonnes each. Herbivores outnumber
carnivores about ten to one in world aquaculture
production.
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The Top Ten Species Produced by
Aquaculture (1998)
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Pacific Oyster
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Crassostrea gigas
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Silver Carp
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Hypophthalmicthys
molitrix
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Grass carp
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Ctenopharyngodon
idellus
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Common Carp
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Cyprinus carpio
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Bighead Carp
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Hypophthalmicthys
nobilis
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Japanese Carpet Shell
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Ruditapes
philippinarum
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Crucian Carp
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Carassius
carassius
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Yesso Scallop
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Pecten yessoensis
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Nile Tilapia
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Oreochromis
niloticus
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Roho Carp
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Labeo rohita
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The aquatic plants produced include brown, red and
green seaweeds, grown for direct use as food and
also for the extraction of alginate and carageenan
(agar-agar). Half of the total 1998
production was of just one species, the Japanese
Kelp (Laminaria japonicus), 90 percent of
which is grown in China.
Freshwater fish are the most important
aquaculture group by volume and make the greatest
contribution to the human food supply. However,
some of the minor product groups such as shrimp and
marine fish have a disproportionate economic
importance because of their high unit value. Farmed
freshwater fish, for instance, had an average value
of US$1.14 per kg in 1998, while marine fish came
in at US$4.35 and crustacea at US$5.90 per kg.
Overall most of the major aquaculture product
groups exhibited a two- to three-fold growth during
the 1990s with some individual species increasing
even more. World production of the Chinese River
Crab (Eriocheir sinensis), for example,
expanded twenty-five fold between 1989 and 1998
(from 5 000 to 123 000 mt). Other notable increases
include the Giant Freshwater Prawn
(Macrobrachium rosenbergii) with a six-fold
growth, the Black Carp (Mytopharyngodon
piceus) with a 4-fold growth and the Japanese
Carpet Shell (Ruditapes philippinarum) with
a 5-fold growth. The sector of high value marine
finfish (such as seabass, grouper and mandarin
fish) is also experiencing a strong expansion
driven by demand in affluent Asian markets,
especially for the live product.
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