FOR RURAL DEVELOPMENT
More than one-fourth of all animal protein consumed by man is aquatic in
origin. Regional differences range from Asia where more than one-fourth of
dietary animal protein is fish to North and South America where less than 10% of
animal protein consumed by man is from aquatic sources.
Aquaculture has
been been practiced in many Asian countries for centuries, but is a new form of
agriculture in many African and Latin American countries. It is defined as the
cultivation of animals and plants in aquatic environments. Aquaculturists
manipulate certain components of the environment to achieve greater control over
production of aquatic organisms than is normally possible in nature.
Figure 1: Increased production of aquatic animals and plants is achieved
through
aquaculture.
BENEFITS OF AQUACULTURE
1)
Productive use of poor agricultural lands
Ponds built on the best
agricultural land have the highest natural productivity. High production from
aquaculture is also possible in ponds built on land which is unsuitable for
other forms of agriculture. Hilly land which is difficult to farm or is easily
eroded can be utilized for fish ponds. Swampy areas or soils with high salt or
heavy clay content can also be utilized for aquaculture.
Figure : Small valleys often have excellent potential for pond
construction.
2) Natural resource conservation
Aquaculture and water
harvesting can contribute substantially to the conservation of natural
resources, especially water and soil. In many developing countries, surface
water is often allowed to drain away instead of being harvested and stored for
beneficial use. The requirement by aquaculture for abundant water provides
justification and opportunity to build ponds for harvesting and storing water.
This also makes water available for supplemental irrigation, stock watering and
domestic needs. Ponds can reduce the dangers
of downstream flooding by
holding water high in watersheds and checking the erosional
force of sudden
runoff. Ponds maintain soil moisture in their vicinity and thus
support
vegetation and wildlife. Ponds on unimproved and unprotected
watersheds trap topsoil
which may be recovered and redistributed to gardens
and fields. Water and soil conservation problems are often greatest in hilly
areas where poorer people live. Topography in these areas lends itself to the
development of watershed ponds.
3) High economic value of aquacultural
products
Aquaculture may produce a cash crop in a subsistence level economy.
Farmers frequently receive higher net returns for fish relative to other
traditional crops. Even small ponds can contribute substantially to farm income
or reduce family spending as fish are sold, bartered or eaten.
Production
costs for fish, poultry, beef and pork have been compared in numerous studies.
Initial construction costs for fish farming are high, but once ponds are built
fish are usually the most profitable to produce. Approximately 2,500 kg of fish
per year is produced in a 1 hectare pond by applying low-cost fertilizers such
as plant cuttings and animal manures. Production from grazing cattle on the same
land area is seldom more than half of that amount. The use of waste materials
from integrated livestock and crop enterprises may also reduce input costs while
raising fish production.
Fish convert food into flesh efficiently. Food
protein is converted to muscle protein with about the same efficiency as
chickens or swine, but they need much less starch for energy. Fish are
essentially weightless in water, and thus expend little energy for locomotion or
to maintain a normal upright position. They are "cold blooded" animals and do
not expend energy to maintain a relatively high body temperature as do poultry,
swine and cattle. Thus, the amount of food energy required to produce a kilogram
of fish is much less than the amount required to produce an equal weight of
terrestrial livestock.
4) High nutritional value of aquacultural
products
Fish is a high quality protein source that ranks about equal to
chicken and is superior, in many respects, to red meats. The edible fraction of
fish is similar to that of other animals (49 - 52% of the whole animal), but
fish flesh contains higher quality and more digestible protein than red meats.
Evidence that fish diets reduce cholesterol levels in the blood is increasing.
Dressed fish contains about one-third less fat than red meats. Fat in fish flesh
is also more unsaturated than that in red meats.
Table 1: Nutritional
value of dressed fish flesh compared with other food animals.
5) Integrated aquaculture is a highly sustainable form of agriculture.
Aquaculture is sustainable because it makes use of locally available resources.
Integration of aquaculture with other forms of agriculture diversifies farm
productivity. This, in turn, provides opportunities for intensified production
with more efficient allocation of land, water, labor, equipment and other
limited capital than enterprises which are independently operated. Stored pond
water may serve as a catalyst for rural development because a variety of
different activities may be simultaneously undertaken. Fish culture integrated
with garden irrigation, livestock watering, and various domestic uses are all
possible.
Figure 3: Aquaculture can be integrated with the production of livestock,
fruits, vegetables
and other water uses.
Culturing several different
fish species with complimentary feeding habits together in the same pond
(polyculture) is more complicated, but utilizes more of the available natural
food organisms. Higher yields are thus obtainable with polyculture than is
possible by culturing a single fish species. Polyculture also permits several
different species that may command different market prices to be grown. A range
of consumer tastes and demands may thus be served from one pond.
Figure 4: Polyculture utilizes more of the available food and produces a
variety of fish for
market.
6) Self-sufficiency for subsistence
farmers
Aquaculture makes fresh fish available in rural areas. There are few
regions in the developing world where fish are not an acceptable protein source.
However, fish captured off the coasts of these countries are often exported and
are too costly for the poor. Large populations of rural poor may live in
isolated areas where transportation and market facilities are inadequate to
provide them with sufficient fish.
Inland ponds allow subsistence farmers
to raise fish for their families. Aquaculture helps them to diversify food
production and promotes self-sufficiency by spreading the risk of crop failure.
Fish are also small packages of protein which can be individually harvested and
consumed as needed, without requiring refrigeration to keep large quantities
from spoiling. This is an added benefit in areas without electricity or
ice.
THE FEASIBILITY OF AQUACULTURE
Aquacultural production
technologies are determined by the interaction of five factors which may be
manipulated to some extent. These are the physical environment, culture
facilities, available nutrient inputs, species cultured and the ability of
producers to balance all the factors in a profitable package.
The natural
environment is essentially fixed, though subject to minor modifications. It
includes such climatic conditions as temperature, rainfall and storm patterns,
land elevation and topography, soil characteristics (particularly water holding
capacity and acidity), water availability and geographical barriers to supplies
and/or markets. If these conditions are not suitable to aquacultural
development, little can be done to change them.
The role of aquaculture
in increasing protein consumption in the world depends on demand. This demand is
determined by consumer income, the cost of alternate foods and a combination of
taste preferences and dietary habits. The ability to make aquaculture profitable
is also affected by traditions regarding land use, time management and
allocation of other resources. Seasonal changes in demand and supply, as well as
social and political factors also affect the feasibility of
aquaculture.
GLOSSARY OF TERMS
aquaculture - raising of
animals or plants in aquatic environments under controlled
conditions.
erosion - the washing away of soil by
rainfall and water as it runs over land.
extensive
aquaculture - raising aquatic animals or plants under
conditions of little or incomplete control over such factors as water flow,
number and weight of species raised, and low quality and quantity of nutrient
inputs.
food conversion efficiency or ratio - a measure of the
amount of dry food required to produce an equal wet weight of aquatic animal
flesh.
independent variable - a condition subject to only minor
modifications, which affects feasibility for aquaculture.
integrated
aquaculture - aquacultural systems integrated with livestock and/or crop
production. For example, using animal manures to fertilize a pond to enhance
fish production and water from the pond to irrigate a
garden.
intensive aquaculture - aquaculture practiced under a high
degree of environmental modification and control in which the principle nutrient
source is high-quality feed.
microscopic - invisible to the eye
without the aid of a microscope or magnifying glass.
phytoplankton
- the plant component of plankton.
plankton - the various,
mostly microscopic, aquatic organisms (plants and animals) that serve as food
for larger aquatic animals and fish.
poikilothermic -
"cold-blooded"; having a body temperature that varies with ambient air or water
temperature.
polyculture - simultaneous culture of two or more
aquatic species with different food habits.
watershed - an area
from which water drains to a single point.
zooplankton - the
animal component of plankton.
Funding for this series was provided by
the United States Agency for International Development. Communications regarding
this and other technical brochures on water harvesting and aquaculture should be
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Information contained herein is available to all persons regardless of race,
color, sex or national origin.