244
mate objective is to build up a signifi cant food
producing industry, analogous to agriculture,
but with a reasonably predictable and controllable yield.
15.6.1 The Present Status
of Aquaculture
Although diffi cult, it may be possible to generate
an approximate estimate of the world aquaculture
production based on the fragmentary and sketchy
statistics of fi nfi sh aquaculture. The total yield
for the year 1975 was calculated as 6.0 million mt
(wet weight approx.). This was <10 % of the estimated total world fi sh catch for the same year.
Nevertheless, it refl ected >50 % increase since
1970 (Pillay 1976 ). On the other hand, countries
like Japan, Poland and Romania had recorded
two- to fi vefold augmentation during this period
of half a decade. Nevertheless, there is considerable growth potential of aquaculture although the
yield sometimes is relatively low.
It may be noted here that >100 species of plants
and animals are cultured in aquaculture practices.
But >60 % of the total aquaculture yield comes
from pond culture of a few species of fi nfi sh only.
These include the rainbow trout ( Salmo gairdnerii ),
channel catfi sh ( Ictalurus furcatus ), mullet ( Mugil
spp.) and milkfi sh ( Chanos chanos ). Also included
are several species of carps, notably the Indian
major carps ( Labeo rohita, L. gonius, L. calbasu,
Cirrhinus mrigala and Catla catla ), the exotic
carps (notably Cyprinus carpio or the common
carp , Hypothalmichthys molitrix or the silver carp ,
Ctenopharyngodon idellus or the grass carp),
salmons and the tilapias spp.
Notwithstanding the above, there are other
different types of aquaculture in addition to pond
culture of fi shes:
(a) Oyster culture and mussel culture on either
the seabed or suspended from rafts
(b) Culture of scallops, clams, Veneridae,
Solenidae, cockles, etc., on controlled areas
of seabed
(c) Pisciculture in fl oating cages
(d) Farming of shrimps (penaeids) and FW
prawns ( Macrobrachium spp.)
(e) Abalone ( Haliotis spp.) culture
(f) Culture of marine algae or ‘seaweeds’
(g) Turtle, terrapin farming, etc.
Except some, like the Japanese cultured
pearl industry, almost all aquaculture products
are meant for direct human consumption. Large
marine algae (commonly called ‘seaweeds’),
numbering approx. 30 genera, are grown commercially mainly for industrial purposes. The
Japanese raise certain red algae (notably the
Porphyra species) for human consumption.
This ‘nori’ culture produces c 120,000 wet mt
of high- quality food annually which is said to
contain about 30–50 % of protein on a dry
weight basis. However, most of the red, green
or brown macroalgae, which are harvested or
cultured by man, contain pentosans (5-carbon
carbohydrates), compounds which are not easily digested by mammals. These algae are generally used as a source of vegetable gums
(alginates and agar- agar) instead of food. These
are included in a range of products like pharmaceuticals, paper, adhesives, textile sizing and
synthetic rubber.
15.6.1.1 Geographical Sources
of Aquaculture Production
The Indo-Pacifi c region is an area bounded
roughly by Pakistan on the west, Japan and
Philippines on the east, and Australia to the
south. Approximately 75 % of the total world
aquaculture yield is obtained from the IndoPacifi c region. The traditional ponds and
fl ooded rice fi elds in the Indian subcontinent
including Bangladesh account for a big share
in the total global aquaculture production.
Likewise, the almost similar habitats in the
People’s Republic of China produce approx. a
third of the total world production. Japan,
Korea, Taiwan, Indonesia, the Philippines, etc.,
are some of the other important aquaculture
countries in this region.
Contrary to the above, the development of
aquaculture in most of the western countries has
been remaining a little sluggish since few years. It
could be mainly due to low market demands,
intense competition, high costs of potential sites for
aquaculture installations, and so on. For example,
15 Wetland Flora, Plankton, Productivity, Fauna and Fishes
mate objective is to build up a signifi cant food
producing industry, analogous to agriculture,
but with a reasonably predictable and controllable yield.
15.6.1 The Present Status
of Aquaculture
Although diffi cult, it may be possible to generate
an approximate estimate of the world aquaculture
production based on the fragmentary and sketchy
statistics of fi nfi sh aquaculture. The total yield
for the year 1975 was calculated as 6.0 million mt
(wet weight approx.). This was <10 % of the estimated total world fi sh catch for the same year.
Nevertheless, it refl ected >50 % increase since
1970 (Pillay 1976 ). On the other hand, countries
like Japan, Poland and Romania had recorded
two- to fi vefold augmentation during this period
of half a decade. Nevertheless, there is considerable growth potential of aquaculture although the
yield sometimes is relatively low.
It may be noted here that >100 species of plants
and animals are cultured in aquaculture practices.
But >60 % of the total aquaculture yield comes
from pond culture of a few species of fi nfi sh only.
These include the rainbow trout ( Salmo gairdnerii ),
channel catfi sh ( Ictalurus furcatus ), mullet ( Mugil
spp.) and milkfi sh ( Chanos chanos ). Also included
are several species of carps, notably the Indian
major carps ( Labeo rohita, L. gonius, L. calbasu,
Cirrhinus mrigala and Catla catla ), the exotic
carps (notably Cyprinus carpio or the common
carp , Hypothalmichthys molitrix or the silver carp ,
Ctenopharyngodon idellus or the grass carp),
salmons and the tilapias spp.
Notwithstanding the above, there are other
different types of aquaculture in addition to pond
culture of fi shes:
(a) Oyster culture and mussel culture on either
the seabed or suspended from rafts
(b) Culture of scallops, clams, Veneridae,
Solenidae, cockles, etc., on controlled areas
of seabed
(c) Pisciculture in fl oating cages
(d) Farming of shrimps (penaeids) and FW
prawns ( Macrobrachium spp.)
(e) Abalone ( Haliotis spp.) culture
(f) Culture of marine algae or ‘seaweeds’
(g) Turtle, terrapin farming, etc.
Except some, like the Japanese cultured
pearl industry, almost all aquaculture products
are meant for direct human consumption. Large
marine algae (commonly called ‘seaweeds’),
numbering approx. 30 genera, are grown commercially mainly for industrial purposes. The
Japanese raise certain red algae (notably the
Porphyra species) for human consumption.
This ‘nori’ culture produces c 120,000 wet mt
of high- quality food annually which is said to
contain about 30–50 % of protein on a dry
weight basis. However, most of the red, green
or brown macroalgae, which are harvested or
cultured by man, contain pentosans (5-carbon
carbohydrates), compounds which are not easily digested by mammals. These algae are generally used as a source of vegetable gums
(alginates and agar- agar) instead of food. These
are included in a range of products like pharmaceuticals, paper, adhesives, textile sizing and
synthetic rubber.
15.6.1.1 Geographical Sources
of Aquaculture Production
The Indo-Pacifi c region is an area bounded
roughly by Pakistan on the west, Japan and
Philippines on the east, and Australia to the
south. Approximately 75 % of the total world
aquaculture yield is obtained from the IndoPacifi c region. The traditional ponds and
fl ooded rice fi elds in the Indian subcontinent
including Bangladesh account for a big share
in the total global aquaculture production.
Likewise, the almost similar habitats in the
People’s Republic of China produce approx. a
third of the total world production. Japan,
Korea, Taiwan, Indonesia, the Philippines, etc.,
are some of the other important aquaculture
countries in this region.
Contrary to the above, the development of
aquaculture in most of the western countries has
been remaining a little sluggish since few years. It
could be mainly due to low market demands,
intense competition, high costs of potential sites for
aquaculture installations, and so on. For example,
15 Wetland Flora, Plankton, Productivity, Fauna and Fishes