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Report 4 (of 6): Fishy Business
- Peru
Introduction
In many parts of the world, fish provide
an important part of people's diets. Now, due to technological
innovations and the subsequent increase in the quantity
of fish caught, overfishing has caused a global decrease
in fish stocks. One answer is to breed fish for food.
As in agriculture, fish farming involves the removal
of unwanted plants and animals and their replacement
by desirable species. Fish farming can be combined
with agriculture, animal husbandry and irrigation
practices to more efficiently use local resources,
while increasing production and income.
In Peru, fishing is the second largest
economic activity and a significant source of income
and jobs for its population. Commercial fish farming
in Peru is based mainly on the production of shrimp,
trout, scallops and tilapia. Fishing is particularly
important in Iquitos, capital of the department of
Loreto and the largest city in the northern Peruvian
jungle. Subsistence fishing here represents 75 per
cent of the total production of the Peruvian Amazon,
with native communities such as the Cocamas, Witotos,
Boras and Ticunas, using the surrounding rivers of
the Nanay, Itaya and Amazon to fish for food. Yet
population growth has led to overexploitation of natural
fish stocks, endangering species and creating food
shortages. Now a project being directed by the Italian
non-governmental organisation, Terra Nuova, is helping
communities to create a city-wide network of sustainable
fish farms.
Iquitos
In the past two years fish farmers
between the cities of Iquitos and Nauta have been
supported with aquaculture extension activities. The
Food Security Program for Familiar Productive Units
or PROSEAL is being directed by Terra Nuova together
with IIAP, the Instituto de Investigaciones de la
Amazonia Peruana. The programme has been promoting
the organisation of fish farmers into self-sustainable
associations, developing the aquaculture industry
in a coordinated way. This allows farmers to interact
and be educated together.
PROSEAL has been developing ongoing
workshops aimed at teaching local fish farmers about
the production process, ranging from pond construction
and pond management to commercialisation of their
product. All activities are directed at native fish
species with fingerlings (young fish) produced by
IIAP and distributed among PROSEAL members. To date
PROSEAL has greatly impacted the aquaculture industry
in the Iquitos region. They now provide services to
88 per cent of fish farmers who account for over half
the total fishponds in the region.
In Iquitos, one of the most important
fish is the paiche (Arapaima gigas). Weighing
up to 200 kilos and measuring some 3 metres, paiche
is the biggest freshwater fish in the world, found throughout
the Amazonian River Basin. Due to high demand and intense
fishing, fishermen have had to go ever further into
the network of rivers and lakes to find paiche fish
of a reasonable size. Its fine meat makes it popular
in regional, national and international markets and
a favourable choice for fish farming.
Types of Fish Farm
There are many different methods of
enclosing fish on a farm, including earth ponds, concrete-lined
ponds, concrete raceways, concrete tanks, fibreglass
tanks, netting enclosures and floating cages. Earth
ponds are perhaps the most commonly used in fish farming
around the world. This particular farming system is
dependent on the natural production of fish feed in
the pond, with the earth bottom functioning as an
important ecosystem, similar to a field in land farming.
Earth ponds are common as they are the easiest to
construct and the cheapest per unit area of pond.
Fish Farming in Ponds
The majority of freshwater fish are
raised in ponds. Water is taken from a lake, river,
well or other natural source and is directed into
the pond. Fish farming ponds range in size from a
few hundred square metres to several hectares (one
hectare is about 2½ acres), and are located on land
that has a gentle slope. Generally, small ponds are
used for spawning and fingerling production.
Fish farming in Peru © ISIS
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There are effectively two types of
pond; those built on the ground and those built in
it. Those built on the ground retain water by a dam,
dyke or embankment, usually at a level above the surrounding
ground. This is often preferred as it can be easily
drained, helping the harvesting of the fish and the
maintenance of the pond. With those built in it, water
is allowed to collect in the excavated area, the water
surface being at or below ground level.
The most important natural factors
when planning a fish farm concern land, water and
climatic conditions. Naturally important areas, such
as mangrove forest, should not be used for fish farming,
but abundant good quality water is very important.
The properties of the proposed site will determine
the type of fish that can be grown.
Advantages of fish farming in ponds
include:
- High quality animal protein is
provided for human consumption.
- Their integration into existing
farm systems creates additional income and improves
on-farm water management.
- Fish growth and species selection
can be controlled.
- Fish produced are the owner's property
and can be harvested at will.
- Fish are located close by.
- Marginal land too poor or costly
for agriculture can be used.
- Ponds can be used year after year.
As fish need protein to grow and reproduce,
they can compete for products that could otherwise
be used directly for human consumption. In addition,
the cost of production can be quite high if self-financed,
making fish farming less financially competitive than
with fish caught in the wild. The high initial investment
and production costs of setting up a fish farm mean
that prospective farmers need to consider some important
factors before deciding to undertake fish farming,
including:
- Finance An estimate of costs
should be made including the land, fish stock, pond
construction, labour, production and harvesting.
- Site selection The soil
must be able to hold water and good water quantity
and quality should be available at reasonable cost.
The site should be close to home and potential losses
from poaching should be estimated. The site and
roads should be passable and not subject to flooding.
- Fish stock Stock can either
be bred by the farmer or bought from others. If
breeding on site is preferred, there must be enough
space for maintenance of brood stock and for the
production of fingerlings. If the stock is bought,
a reliable source of good quality fish stock is
required.
- Harvesting It is important
to ensure there is sufficient labour to harvest
the fish. The most economical harvesting method
should be used and storage facilities may be needed
for harvested fish.
Other methods of fish farming include
using dam and reservoir waters stocked with fingerlings
or fry which can be harvested with nets; cage culture
where flowing water is used to grow small fish in
cages; and growing fish in pens inside lakes or offshore
areas.
Considerations
Assessing whether a potential site
is suitable is only the first step towards fish farming
in ponds. Site selection depends on the kind of fish
to be farmed, and consideration needs to be given
to soil type, quality and quantity of water available,
and the requirements for filling and draining the
pond.
Site
The ideal position for a pond is one
where it can receive a water supply and discharge
used water using the natural slope of the land. The
land contour and land slope therefore determines which
way to build the pond. Totally flat land and hilly
land with a gradient of more than 4 per cent are both
unsuitable for pond construction. Ideally, side slopes
should be at a ratio of 2:1 or 3:1, meaning each metre
of height needs 2 or 3 metres of horizontal distance.
Once a site has been chosen, all vegetation, trees
and shrubs must be removed to stop the material rotting,
forming escape holes for the water and decreasing
water retention.
Soil
Soil quality affects both productivity
and water quality in a pond. The pond bottom must
be able to hold water (low porosity) and contribute
to water fertility by providing nutrients. For these
reasons clay soil is preferred, or soil that contains
a minimum of 25 per cent clay. With light soils, it
can be possible to mix with clay to give a watertight
covering to the pond bottom. Sandy soils and rocky
soils are unsuitable.
There are three consecutive methods
used to determine whether soil is suitable for pond
construction, the squeeze method; groundwater test;
and water permeability test.
- Squeeze method Wet a handful
of soil with just enough water to make it moist,
then squeeze the soil and, if it holds its shape
after opening the palm, the soil will be good for
construction.
- Groundwater test This test
should be done during a dry period. Dig a hole 1
metre deep and cover it with leaves for one night
to limit evaporation. If the hole is filled with
ground water the next morning a pond could be built
but draining the pond may take longer due to high
groundwater levels. If the hole is still empty,
no problems will occur as a result of high groundwater
and the site may be suitable.
- Water permeability test
Fill the same 1 metre deep hole with water to the
top, and cover with leaves. The next day the water
level should be lower due to seepage. Refill the
hole to the top and cover with leaves once more
and check the water level the following day. If
the water level is still high, the soil is impermeable
enough and suitable for pond construction. If the
water has disappeared, the site is unsuitable unless
the bottom is first covered with plastic or heavy
clays.
Dykes
Generally, a pond is constructed by
excavating the pond area and using the excavated material
to form the pond sides, known as the embankments or
dykes. Dykes are built up of compacted layers
of soil 20-30 centimetres (8-12 inches) thick, usually
rammed with a heavy wooden pole to ensure water tightness
and strength. Dykes tend to sink as they settle, so
the height of a newly compacted dyke should be approximately
20 per cent higher than desired. All the earth used
in construction should be damp to aid compaction. When
dykes are built on permeable soil they must be constructed
of impermeable soil or have a central core of impermeable
material at least 45 cm (18 in.) thick. This core must
go down below the level of the pond bottom to form an
impermeable barrier. Alternatively a dyke constructed
of permeable soil can be constructed on the inside with
impermeable material. In this case the permeable layer
must be carried down below the pond bottom (see diagram).
Water
Ponds must be located near a good
supply of water such as a spring, stream, lake or
reservoir with plenty of water all year round. Water
flow into a pond is needed to meet the oxygen demands
of the fish, to remove their waste products before
they reach harmful levels and to make up for losses
caused by seepage and evaporation. Water temperature
is important too and determines the species selected
to be raised. A water temperature between 20 ºC and
30 ºC (degrees Celsius) is generally recommended.
The water depth is usually 30 cm at
the shallow end and 1 metre at the deep end. The pond
can be deeper than this if it is used as a water reservoir
during the dry season. The next step is to check the
water quality to find out whether it is clear or muddy
and murky. Muddy or murky water will interfere with
the fish's breathing and settle on the bottom of the
pond, blocking drainage channels.
Building the Pond
Building the pond is the most difficult
part of fish farming. A well-built pond is a good
investment that can be used for many years. The steps
in building a fish pond are:
- Preparing the site
- Building a clay core (only necessary
for contour ponds)
- Digging the pond and building the
dykes
- Building the inlet and outlet
- Protecting the pond dykes
- Fertilising the pond
- Fencing the pond
- Filling the pond with water
- Checking for problems before stocking
fish
Fish Selection
When selecting fish species suitable
for farming, factors such as the market price and
demand, growth rate and the ability to reproduce in
captivity, need to be considered carefully. Fish farmers
who do not breed their own fish depend on fingerling
supply. Fish farmers need a reliable supply of healthy
fingerlings to stock grow-out ponds. Farmers can produce
their own fingerlings, purchase the fingerlings from
hatcheries, or use a combination of both options.
In fish farming, feeding costs are generally
the most important in the total cost of production.
Plant eating (herbivorous) or plant and animal eating
(omnivorous) fish species are preferable, as they will
feed on natural food resources occurring in the pond.
Predatory (carnivorous) species need a high protein
diet and so are more expensive to produce, but most
do fetch a higher market price. It is possible to increase
the quantity of natural food by fertilising the water.
The fertiliser or manure's organic and mineral nutrients
are used by bacteria and plants, which are then consumed
by filtrating organisms such as zooplankton.
These organisms are then eaten by the fish, which greatly
improves production.
Fish species that are resilient and
can tolerate unfavourable culture conditions will
survive better in poor environmental conditions. The
influence of the species themselves on the environment
should also be considered. Newly introduced fish species
should:
- fill a need that cannot be fulfilled
by local species;
- not compete with local species;
- not cross with local species and
produce undesirable hybrids;
- not introduce diseases and parasites;
and
- live and reproduce in balance with
the environment.
Raising different fish species together,
known as polyculture, ensures fish production
is higher than when fish species are raised separately,
known as monoculture. When monoculture is practised
it is easier to give supplementary foods as there
is only one species to consider. However, a single
disease may kill all the fish in the pond. When polyculture
is practised, natural food resources tend to be better
utilised due to diversity, and fish production can
be raised to a higher level than with only one species.
There are many other issues that need
to be covered for a successful fish farm to function
properly. These include fish nutrition and food, health
and disease, reproduction, harvesting and pond maintenance
and monitoring.
References
Small-Scale Freshwater Fish Farming:
Agrodok 15
A. van Eer, T. van Schie, A.D. Hilbrands
Aquaculture Training Manual
D. Swift
Backyard Fish Farming
P. Bryant, K. Jauncey, T. Atack
Further Information on Fish Farming
in Peru:
Terra Nuova
Av. Abelardo Quiñónez
Km. 2.5. Iquitos
Peru
Website: http://www.aamterranuova.it/
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Amazon Research Institute
Peruana Programa de Ecosistemas Acuáticos
Av. Abelardo Quiñónez
Km. 2.5. Iquitos
Peru A.P. 784 |
Further Reading
Books from ITDG Publishing
Small-Scale Freshwater Fish Farming:
Agrodok 15
A. van Eer, T. van Schie, A.D. Hilbrands
£5.95, 1996, ISBN 9072746724
Fish Farming in Tropical Fresh
Water Ponds
£13.75, STOAS, 2000, ISBN: 9052850097
This manual introduces the basic principles of freshwater
fish farming in the tropics. A VSO aquaculture team
working in agricultural education in Thailand originally
prepared this text. This book is supplemented with
a second volume - Integrated Fish Farming in the Tropics.
Both volumes are also available as a set for £23.75
Books from the Food and Agricultural
Organisation (FAO)
Handbook of small-scale freshwater
fish farming
V. Gopalakrishnan, A.G. Coche
US$29, FAO, 1999, ISBN: 9251031630
Available to download for free at: www.fao.org/docrep/T0581E/T0581E00.htm
This document is an output from
a project funded by the UK Department for International
Development (DFID) and the European Commission (EC)
for the benefit of developing countries. The views
expressed are not necessarily those of DFID or the
EC.
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