Tài liệu STRATEGIC ENVIRONMENTAL ASSESSMENT on shrimp farms in the southeast of Thailand docx

Minor Field Studies No. 176
_______________________________________________________________________
Swedish University of Agricultural Sciences
International Office
Uppsala, November, 2001
ISSN 1402-3237
STRATEGIC ENVIRONMENTAL ASSESSMENT
on shrimp farms in the southeast of Thailand
Teresia Lindberg and Anna Nylander
Supervisor in Sweden:
Hans-Georg Wallentinus, Associate Professor and Director of the EIA Center, SLU,
Department of Landscape Planning Ultuna, Uppsala
Supervisor in Thailand:
Magnus Torell, Project leader at ICLARM
The Minor Field Studies series is published by the International Office of the Swedish
University of Agricultural Sciences.
Minor Field Studies are carried out within the framework of the Minor Field Studies
(MFS) Scholarship Programme, which is funded by the Swedish International
Development Cooperation Agency (Sida).
The MFS Scholarship Programme offers Swedish university students an opportunity to
undertake two months´ field work in a developing country to be analysed, compiled
and published as an in-depth study or graduation thesis work. The studies are primarily
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supported by Swedish development assistance.
The main purposes of the MFS programme are to increase interest in developing
countries and to enhance Swedish university students´ knowledge and understanding of
these countries and their problems and opportunities. An MFS should provide the
student with initial experience of conditions in such a country. A further purpose is to
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administers the MFS programme for the rural development and natural resources

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Tryck: SLU/Repro, Uppsala 2001
Preface
This Minor Field Study (MFS) was performed by Teresia Lindberg and Anna Nylander, who
are both studying Eco-toxicology at Uppsala University in Sweden. The report is a Master´s
thesis for Teresia Lindberg.
The Swedish International Development Agency (Sida) finances a number of so-called Minor
Field Studies for students or young people to carry out a research project in a developing
country. The study usually takes place in one of Sida´s target countries and is part of a local
Sida-sponsored aid programme. The study was located on the south east coast of Thailand
with the Coastal Resources Institute (CORIN) at the Prince of Songkhla University in Hat Yai
as a study centre. The field work was carried out from the end of February until the end of
April, 2001.
A number of people have been a great help for us during our study. We would first like to
thank our supervisor Hans-Georg Wallentinus at the Department of Landscape Planning
Ultuna, SLU for help and support and Magnus Torell at ICLARM for providing us with very
useful contacts in Thailand.
At CORIN in Hat Yai we would like to thank Somsak Boromthanarat and Ayut Nissapa for

letting us work at their office and for helping us with contacts.
We would also like to express our gratitude to Siri Tookwinas at the Department of Fisheries
in Bangkok, Noparat Bamroongrugsa at the Prince of Songkhla University, Putth
Songsangjinda at the Department of Fisheries in Songkhla, Max Andersen at DANCED
(Danish Co-operation for Environment and Development) in Ranod and Jim Enright at The
Mangrove Action Project in Trang for assistance during our field study. A special
appreciation to Simon Funge-Smith at FAO in Bangkok who has been a tremendously good
source of information both in Thailand and when questions turned up in Sweden.
Sara Gräslund at the Institute of Applied Environmental Research at the Stockholm
University and Johan Sundberg at Sida have provided us with informative material.
Last, but not least our sincere thanks to all helpful and friendly Thai people and especially the
shrimp farmers.
Abstract
This Strategic Environmental Assessment was carried out in order to collect up-to-date
material about the situation of the coastal shrimp farming industry in the south east of
Thailand and to compare different shrimp farming methods. The semi-closed intensive shrimp
farming system, which is the most commonly applied farming method in Thailand, is
compared with a closed farming system where the water is recirculated and a system where
the sludge is removed on a regular basis. The study was performed in five provinces on the
southeast coast of Thailand where, during the spring of 2001, the authors interviewed shrimp
farmers as well as expertise at Departments, University institutions and Environmental
organisations.
The black tiger shrimp dominates the Thai production and about 90% of the cultivated
shrimps are exported for luxury consumption in industrialised countries. Marine shrimp
farming has expanded greatly during recent decades and can today be found in every coastal
province of the country. The intensive farms have been constructed by converting a variety of
land uses, including former extensive shrimp farms, mangroves, rice paddies and other
plantations.
The environmental and socio-economic impacts of the different shrimp farming systems are
described in the report and the alternatives are evaluated and compared with each other with

reference to the different impacts. The main environmental impacts are due to chemical use,
mangrove destruction, salinisation, eutrophication, sedimentation, extraction of ground water
and spread of diseases and genes. The socio-economic impacts are, for example, health
problems, loss of livelihood and fresh water resources, impacts on agriculture, marginalisation
and changes in employment.
According to the comparison, it is apparent that the semi-closed system has the most negative
environmental and socio-economic impacts. Both the closed recirculating system and the
sludge removal system have less negative impacts on the environment and on the social and
economic systems than the semi-closed farming system. Concerning mangrove forest
destruction, extraction of ground water and loss of mangrove values and products, the
alternatives give no impact at all.
The closed recirculating system is considered to be the most sustainable alternative due to the
many issues where no negative impacts occur. This is only true providing that the system is
successful despite some managerial problems. If the system should not work entirely, the
sludge removal system or a closed recirculating system without waste water recirculation are
still much more sustainable alternatives than the semi-closed farming systems that are used in
Thailand presently.
The major problems connected to the two alternative methods described in this report are the
high construction and operation costs. It is not realistic to expect a poor farmer to adopt one of
the alternative systems described in this report without external economic support. A
reasonable possibility for a farmer could be to continually invest in more sustainable methods.
Keywords: Shrimp farming, aquaculture, ecotoxicology, strategic environmental assessment,
environmental impacts, socio-economic impacts, intensive shrimp farming, chemicals,
mangrove forest, Thailand.
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1. INTRODUCTION 4
1.1 Objectives 4
1.2 Methodology 4
2. SCOPE 5
3. DEFINITIONS AND GLOSSARY 7

4. HISTORY 11
5. PRESENT STATUS OF SHRIMP FARMING IN THAILAND 13
6. ENVIRONMENTAL SETTINGS 16
6.1 Black tiger shrimp (Penaeus monodon) 16
6.2 The natural cycle of shrimp development 16
6.3 The mangrove forest 16
6.4 Hatcheries 18
6.5 Grow-out techniques 19
6.6 Inland shrimp farming 21
6.7 Production process and water treatment 21
6.8 Diseases of cultured black tiger shrimp 23
6.9 Artificial shrimp feed 24
6.10 Chemicals and biological products 25
7. DESCRIPTION OF THE ALTERNATIVES 28
7.1 Zero alternative: Semi-closed intensive system 28
7.2 Alternative 1: Closed recirculating system 29
7.3 Alternative 2: Sludge removal system 30
8. ENVIRONMENTAL IMPACTS 31
8.1 Mangrove deforestation 31
8.2 Physical barriers 32
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8.3 Pollution by chemicals and water treatment products 33
8.4 Sedimentation 34
8.5 Salinisation and the extraction of groundwater 35
8.6 Eutrophication and water quality issues 37
8.7 Energy usage 39
8.8 Diseases and genetic pollution 40
8.9 Trawling for wild brood stock and for fish meal 41
8.10 Decreased need for trawling wild shrimp 42
9. SOCIO-ECONOMIC IMPACTS 43

9.1 Land conversion and loss of livelihood 43
9.2 Employment and inequity 44
9.3 Public health problems 45
9.4 Impacts on the agriculture 47
9.5 National versus local economy 48
10. EVALUATION OF THE ALTERNATIVES 50
10.1 Evaluation of the alternatives concerning environmental impacts 50
10.2 Evaluation of the alternatives concerning socio-economic impacts 52
11. CONCLUSION AND DISCUSSION 55
12. MITIGATION 57
13. SUSTAINABILITY ISSUES 62
14. UNCERTAINTIES 65
15. REFERENCES 66
APPENDIX 1. GOVERNMENT REGULATIONS AND PLANNING 72
APPENDIX 2. CHEMICALS COMMONLY USED IN THAILAND 76
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APPENDIX 3. DIRECT AND INDIRECT PRODUCTS FROM THE MANGROVE
FOREST 78
4
1. Introduction
1.1 Objectives
The aim of this study was to collect up-to-date material about the situation of the shrimp
farming industry in the southeast of Thailand and to compare the most common shrimp
farming method in Thailand with two other, hopefully more sustainable, methods. This was
done by making a Strategic Environmental Assessment (SEA). The reason for this study was
to assist the Swedish International Development Cooperation Agency, Sida, in their
investigation of possible future support to shrimp farming.
The present work is part of a larger study on shrimp farming, which is being performed by the
EIA-centre at SLU on behalf of Sida. One of the goals with this study is to be able to set up a
checklist for review of Environmental Impact Assessments (EIAs), including SEAs, for

shrimp farming. EIAs are always needed in project proposals, which are submitted to Sida for
assessment. Both the Rio Declaration and the Agenda 21 emphasise the importance of using
EIAs in development co-operation.
A purpose of this SEA is to add to Sida´s EIA-handbook. The report can hopefully also be
used to facilitate and improve the EIA-process for project directors and consultants.
1.2 Methodology
The study includes interviews with shrimp farmers and with expertise at Departments,
University institutions and Environmental organisations. Employees at feed processing
factories and independent researchers were also interviewed. Most of the shrimp farms were
family-owned, but some were big shrimp farming companies such as Chareon Pokphand
(CP-company) or research farms like the DANCED funded shrimp farm in Ranod and the
Department of Fisheries shrimp farm in Songkhla. Field observations and literature studies
were also performed in this study.
The material is summarised and compared in a Strategic Environmental Assessment (SEA).
This report is a back-casting SEA, which means that it investigates the impacts of already
existing shrimp farms.
Environmental Impact Assessment (EIA) is a process that examines the environmental
consequences of development actions in advance. EIA is also a document that should describe
and compare different alternatives. The zero-alternative, which describes the situation
providing that nothing changes in the future, should be included in the comparison. An EIA
shall take into consideration direct or indirect effects on:
• People, flora and fauna
• Land, water, air, climate and landscape
• Material assets and cultural heritage
• Interaction between the above-mentioned factors
The assessment how a project relates to environmentally sustainable development should be
performed in a holistic perspective. Therefore, equally environmental, health-related, social
and economic aspects should be considered.
5
SEA is a relatively new tool and has not yet been so widely applied in practice. Therefore

there is no determined, defined method for how a SEA should be prepared and applied. While
EIAs are made for specific projects, Strategic Environmental Assessments are used for
programmes, policies and plans that are loosely structured and that are continuously reformed.
A SEA has more diverse angles of approach than an EIA and the work takes place on an all-
embracing level. A project EIA deals, for example, first with the question how a project or an
activity shall be worked out, while a SEA concentrates on the questions if various projects are
suitable to carry through and if so where they are to be located. Even the question why can be
important to raise (Naturvårdsverket, 2000).
In addition to what has been written on EIAs above, the SEA should, according to Sida,
include (Sida, 1998):
• A description and analysis of the environmental situation in the sector/region in question.
• A description and analysis of environmental work in the sector, including legislation and
environmental regulations.
• Other relevant information on the institutional situation.
• An analysis of the combined effects of different activities/measures in the
sector/programme.
• Proposals for capacity building measures for environmentally sustainable development in
the sector/programme.
Due to different figures in the literature and at interviews concerning, for example, production
and the frequency of different shrimp farming systems, it has sometimes been hard to select
information. However, the most reliable information according to the authors´ estimations has
been chosen.
2. Scope
In this document we have accepted that the Thai shrimp industry is already developed, thus
issues of sustainability must focus on maintaining production, increasing resource use
efficiency and minimizing further impact on coastal resources. Therefore this report excludes
the assessment of extensive and semi-intensive shrimp farming. We believe that it is
impossible to move backwards in terms of development and technology. The fact that it is
forbidden to construct shrimp farms in the mangrove forest in Thailand today is yet another
reason for excluding these farming systems from the study. There are very few extensive and

semi-intensive shrimp farms left in Thailand today.
In this report three different shrimp farming systems are discussed and compared. Semi-
closed intensive shrimp farming is the most common method in Thailand today and is
therefore the zero-alternative. This alternative is divided into two examples: zero-alternative
A that is situated in a coastal area far away from the mangrove forest and zero-alternative B
that is located in a mangrove area. The two other alternatives are the closed, recirculating
system and the sludge-removal system. Both these systems are under development. It is
concluded that a combination of these two alternatives is not economically possible, even
though it might be more sustainable.
The geographical constraint is the southeast coast of Thailand. That includes five provinces:
Surat Thani, Nakhon Sri Thammarat, Pattalung, Songkhla and Pattani (Figure 1). The focus of
this report is on environmental impacts. To a certain degree we have also evaluated social and
economic impacts. This document focuses on coastal shrimp farming. However, inland
6
shrimp farming is an important issue in Thailand. The activity still proceeds although the
activity was banned in Thailand in 1998. Therefore, this shrimp farming method is not
included in the impact assessment. Related industries such as hatcheries and processing
factories are issues that are too large to be evaluated within the allowed time frame. The
construction phase in shrimp farming is only mentioned briefly in the report.
Our time perspective is about ten years, since a common shrimp farm in Thailand today can
be operated during a maximum of this time.
Figure 1. A map showing the geographical constraint of the study.
The provinces included in the study are Surat Thani, Nakhon Sri
Thammarat, Pattalung, Songkhla and Pattani.
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3. Definitions and glossary
Abandoned shrimp farm In this report, the term abandoned refers to a shrimp
farm that is out of production.
Algicide A pesticide which kills algae.
Anaerobic decomposition Decomposition without the presence of oxygen.

Antibiotic resistance Overuse of antibiotics may lead to the development of
resistant strains of micro-organisms.
Alkalinity Alkalinity is the measure of the total amount of
calcium, magnesium, potassium, phosphorus, boron,
silicon and others. The purpose of knowing the
alkalinity is to understand its ability to neutralise acids.
Aquaculture Farming of aquatic organisms including fish,
molluscs, crustaceans and aquatic plants.
Bactericide A pesticide which kills bacteria.
Baht The Thai currency. (In the spring of 2001,
45.7 baht = 1 US$.)
Bioaccumulation An increased concentration of chemicals in an
organism.
Biocide A chemical that kills living organisms.
Biomagnification The result of biomagnification is that animals at the
"top" of their food chain have higher contaminant
levels than animals at the "bottom". The compounds
accumulate in the bodies
Black tiger shrimp A shrimp species that is named for its big size and
banded tail.
B.O.D Biological Oxygen Demand.
Breeding The process of sexual reproduction and bearing of
offspring.
By-product A secondary product.
Calcification Shell production, making the shell hard by taking up
calcium.
Carnivore A flesh-eating animal.
8
Cation A positively charged ion.
Chemical residue The remains of a chemical compound, in this case in

the shrimp body.
Closed system The water in the grow-out pond is held in the pond
during the whole grow-out period. Only at harvest the
water is released. Even though seepage occurs it is a
closed system.
Crustaceans An animal class that includes shrimp, crab and lobster
etc.
CP Charoen Pokphand
Diesel Fossil fuel producing carbon dioxide, carbon monoxide,
nitrogen oxides, sulphur oxides, partially combusted
hydrocarbons and soot particles.
DOF Department of Fisheries
Dugongs Endangered species of the animal order Sirenia, see
cows.
Ectoparasites Parasites, that live on the outside of its host´s body.
EIA Environmental Impact Assessment
Extensive shrimp farm See the chapter “Grow-out techniques”.
Fungicide A pesticide that kills fungi.
Greenhouse gas A gas that absorbs infrared radiation, and causes the
greenhouse effect. (Carbon dioxide,
chlorofluorocarbons, ozone, methane and nitrogen
oxides).
GSP Generalized System of Preferences
Immunostimulants Products that stimulate the immune system as well as
kill bacteria.
Intensive shrimp farm See the chapter “Grow-out techniques”.
Inland shrimp farm Inland refers to the land beyond brackish water areas
with zero or near zero salinity in the soil. The brackish
or marine water has to be trucked in from the sea.
9

Juvenile Young organism
Manatees An endangered species of sea cow
Moult The shrimp changes its shell.
Mysis A larva stage before the shrimp metamorphoses into a
post larva.
Nauplii Tiny and newly hatched first stage larva.
Open intensive system See the chapter “Grow-out techniques”.
Pathogens Disease-developing bacteria, virus, fungi or protozoa.
Persistent A compound that is not easily broken down.
Pesticide Any chemical compound used to kill pests that destroy
agricultural production or are in some way harmful to
humans.
Phytoplankton The photosynthesising plankton organism.
Piscicide A pesticide that kills fish.
Post larvae The last stage of shrimp development before reaching
adult size.
Prawn According to FAO terminology, prawns refers to
freshwater species. In common language big “shrimps”
are often called prawns.
Prophylactic Preventional
Probiotics Bacterial-enzyme preparations that compete out
harmful bacteria by introducing “good” bacteria.
Protozoan A group of unicellular or acellular organisms.
Rai 1600 sq.m
RAMSAR The Convention on Wetlands is an intergovernmental
treaty adopted on 2 February 1971 in the Iranian city of
Ramsar.
SEA Strategic Environmental Assessment
Self-pollution The re-use of pond water after water discharge.
Semi-intensive shrimp farm See the chapter “Grow-out techniques”.

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Shrimp According to FAO terminology, shrimp refers to
marine and brackish species. In common language
small “shrimp” are often called shrimp.
Shrimp carapaces The shell of the shrimp.
Spawning To produce offspring.
Stratification Layering.
Trickle-filter A biological filter used for treatment of pond water.
The bacteria on the filter feed on ammonia.
Vibrio Vibrio is a bacteria and is one of the most common
organisms in surface waters of the world. They occur in
both marine and freshwater habitats and in associations
with aquatic animals.
Vibriosis A disease caused by the vibrio bacteria.
Wetland Areas of marsh, fen, peatland or water, whether natural
or artificial, permanent or temporary, with water that is
static or flowing, fresh, brackish or salt, including areas
of marine water the depth of which at low tide does not
exceed six meters.
WSD White Spot Disease
YHD Yellow Head Disease
Zooplankton The animal component of plankton.
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4. History
Traditional extensive shrimp farming first began around 1935 in Rayong and Chanthaburi
provinces east of Bangkok. Rice farmers in mangrove areas were experiencing low yields
because of saltwater intrusion into the rice paddies. Under low-tide conditions the farmers
harvested shrimp for domestic consumption and for the local market. The good prices for
shrimp and the optimal brackish water encouraged farmers to convert their rice fields into
shrimp ponds. A major expansion in extensive shrimp production took place in 1947 when the

price of salt fell drastically. Many small-scale salt producers in the coastal provinces
southwest of Bangkok transformed their salt fields into shrimp farms because of higher profit
(Flaherty and Karnjanakesort, 1995).
By the late 70s the introduction of hatchery technology made it possible for farmers to adopt
semi-intensive production methods in which hatchery-reared seed supplemented wild fry. In
1973, the Department of Fisheries (DOF) began to promote semi-intensive marine shrimp
culture. A shrimp fry hatchery was constructed by the Department of Fisheries to provide
mainly black tiger shrimp to small-scale producers (Flaherty and Karnjanakesort, 1995).
In the early 80s Taiwan was the first country to transform traditional extensive shrimp
cultivation into intensive farming of the Black tiger shrimp and became the leading shrimp
producing nation in the world. Other Southeast Asian countries followed the Taiwanese
example and in many countries this development was supported by international financial
organizations such as the World Bank and the Asian Development Bank (Patmasiriwat et al.,
1998). In the mid 80s, intensive shrimp farming became abundant in the Upper Gulf
Provinces of Thailand. The exploding growth started with increasing export prices for shrimp,
particularly to Japan, and with a regional decrease in the catch of wild shrimp. Another factor
that contributed to this rapid growth was the large decline in the Taiwanese production due to
problems with diseases (CORIN, unpublished). Disease problems among cultured shrimp
producers in Taiwan resulted in a 70% scale-down in production in 1988 and an even more
drastic cut in 1989. The fact that the Taiwanese farmers were gradually willing to share some
of their technology and expertise further contributed to the exploding growth in Thailand
(Flaherty and Karnjanakesort, 1995).
Much of the land converted into intensive shrimp farms in the Upper Gulf Provinces of
Thailand were mangrove forests, nipa palm forests, coconut groves or were used for extensive
and semi-extensive shrimp farming. The people who started the intensive farms had little or
no knowledge of shrimp farming. During 1989-1990 an estimated 45 000 ha of shrimp farms
in the northern part of the Gulf were abandoned due to consistent crop failures (Funge-Smith
and Stewart, 1996). The disease outbreaks that destroyed the crop were due to stress created
by the poor water quality in the Inner Gulf of Thailand. Not only self-pollution by the farms
but also urban, industrial and agricultural waste water carried by some of Thailand’s major

rivers caused the problems. Intensive shrimp farming moved to the eastern provinces towards
the Cambodian border and to the southeastern coast of Thailand, due to the pollution in the
Inner Gulf Area. Finally, shrimp farms started to appear in the upper southern provinces of
both the east coast and the west coast. The farms were established in public mangrove forests
and in areas of poor paddy land along the coast (CORIN, unpublished). These provinces were
more suitable for shrimp farming than the Upper Gulf Provinces because of their location
away from industrial and urban pollution and because they could receive water directly from
the sea rather than through common canals.
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Between 1987 and 1991 a major intensification of production took place in Thailand and the
annual shrimp production rose by 615% (Flaherty and Karnjanakesort, 1995). Since 1990,
cultivated shrimp production has exceeded the production of captured shrimp (Patmasiriwat,
1998). In 1991, Thailand became the largest producer of shrimp in the world and still is
(CORIN, unpublished).
In 1995-97 there was a huge outbreak of disease in Thailand. Water quality deteriorated,
production dropped dramatically and many farmers had to abandon their farms. In 1994, some
provinces in Thailand (for example, Ranong province) lost as much as 90% of their
production for at least one of the crops during the year (Funge-Smith and Stewart, 1996).
During the summer of 1997, the Thai economy collapsed and the government floated the
currency. Since Thai shrimp are usually sold on the international market in dollars, the
effective price of Thai shrimp doubled. For a period of about eight months in 1997 to 1998,
profits from the shrimp farms exploded (Rosenberry, 2001).
The shrimp industry in Thailand had a rough year in 1996 due to impacts of shrimp disease,
environmental problems, increased production costs, a low Japanese yen and an USA
embargo on trawled shrimp. The fall of the Japanese yen in 1996 caused an 18% decrease in
the export of frozen shrimp from Thailand to Japan. The USA imposed a ban on Thai trawled
shrimp caught without a turtle excluder device. The Thai officials claimed that they provided
their shrimp fishermen with the device. Eight months later, when Thailand was believed to
have fulfilled the requirement, the ban was lifted.
By 1998, a clear pattern of disease had developed in Thailand: White Spot Disease (WSD)

tended to hit during the northeast monsoon (October to January) and Vibriosis tended to hit
during the hot season (March and April).
Inland or fresh water shrimp farming depends on low salinity techniques developed in the 90s.
The spread of diseases along the coastal area and shortages of suitable locations along the
coast encouraged shrimp farmers to move inland. Low salinity shrimp culture techniques also
developed to overcome the seasonal constraints and evolved through a process of
experimentation by small-scale farmers and hatchery owners. The collapse of the Thai
economy encouraged the rapid expansion of shrimp farming in Thailand’s central region.
Competition between shrimp farming and other interests, such as tourism and industrial
development elevated the cost of coastal land, which further contributed to the rapid
expansion (Flaherty et al., 1999). Once the technical possibility and economic capability of
Black tiger shrimp culture under low salinity conditions established, inland shrimp farming
expanded rapidly (Flaherty et al., 2000). The Thai government banned the inland shrimp farm
practices in 1998, causing a lot of conflicts between shrimp farmers and rice farmers. Fishery
officials have sometimes refused to enforce the ban since they have earlier invested in the
shrimp business. Many farmers have also refused to comply with the ban (CORIN,
unpublished).
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5. Present status of shrimp farming in Thailand
Thailand is a tropical country in Southeast Asia with a population of about 60 million people
and a total land area of 514 000 sq.km. The country borders to Malaysia, Lao PDR, Myanmar
and Cambodia. Thailand has two long coastal lines, one along the Gulf of Thailand (1870 km)
and one along the Andaman sea (800 km).
Today, Thailand is one of the leading tourism destinations in Southeast Asia. Foreign tourists
visiting Thailand have increased from about 1.2 million in 1975 to roughly 9.5 million in
2000. In 1990, tourism produced about 4 billion US$, only half this income is generated from
the shrimp industry (Huitric et al., 2000). Tourism not only brings good to the country, there
are problems with, for example, garbage and pollution. Rice has been the largest single
foreign exchange earner for more than a century in Thailand; rice exports being in the
forefront of Thailand’s economic development. Even though Thailand now has an

industrialised economy, more than 59% of the country's working population is engaged in
agricultural production. Thailand is still the biggest rice exporter in the world, earning 1.7
billion US$ in 1996 (Flaherty at al., 1999).
The Gulf of Thailand is located to the west of the South China Sea. The Gulf is a semi-
enclosed and relatively shallow sea with a mean depth of 45m and covering a total area of
roughly 320,000 sq.km. Numerous rivers discharge freshwater, sediments and polluting
substances into the Gulf. The low salinity water of the Gulf is even more diluted by rain and
freshwater runoff. Cool and saline water flows into the Gulf from the South China Sea.
Rainfall, tidal currents and monsoons create movements in the water, these activities control
the salinity and turbulence of the Gulf. Monsoons also control the surface currents of the Gulf,
being clockwise during the southwest monsoon and anti-clockwise during the northeast
monsoon.
The areas around the Upper Gulf of Thailand have little water circulation and are actually not
really suitable for aquaculture, since effluents from shrimp farms, industries and households
are in a "closed area". On the contrary, the areas along the Lower Gulf and the Andaman sea
are facing the open sea and therefore have good water circulation and are more suitable for
aquaculture. Around the Gulf there are millions of people receiving their livelihood from fish
and mineral resources from the Gulf. Many more people are affected by changes in the
environment of the Gulf, both if the changes are physical or political.
Southern Thailand stands for 40% of Thailand´s shrimp culture (Thongrak et al., 1997).
Along the southeast coast, shrimp farms are densely located on a strip of coastal land about 1-
2 km wide (Figure 1) which measures about 700 km north to south (Rosenberry, 2001).
Shrimp farm ownership along the coast is a mix of corporate, contracted and small-scale
independent farmers. The small-scale farms are by far the most abundant in this area
(Vandergeest et al., 1999). They are often situated along canals that are flushed by tides and
that flow parallel to the coast. The closeness of the canals keeps the infrastructure costs low.
Shrimp farms taking water directly from the sea are likely to be larger or corporate. The
CP-company and Aquastar are two corporations that have set up contracted farming in the
southeast of Thailand.
In shrimp farms in the south of Thailand there are four basic soil types: clay, lateritic,

mangrove clay and sand. Soil types vary a lot between different shrimp farming areas. For
14
example, in Ranod there is mostly low organic content soil (91%) but also some sand or
sand/clay (5%) and mangrove clay (4%). In Nakorn Sri Thammarat, where mangrove forests
are abundant, the soil type is therefore mostly mangrove clay. The soil type is an important
factor, since it affects the pond environment. The soil types affect the accumulation of
sediments in the pond, the amount of organic matter, water seepage, acidity and the ease of
phytoplankton management. Shrimp farms are often constructed on land with low agricultural
potential and therefore the costs are low (Funge-Smith and Stewart, 1996).
Marine shrimp farming has expanded and can today be found in every coastal province of the
country. In 1995, there were about 26 000 shrimp farms in Thailand (Patmasiriwat et al.,
1998) and 40% of the area along the coast in southern Thailand is used for shrimp farming.
Farms have been constructed by converting a variety of land uses, including former extensive
shrimp farms, mangroves, rice paddies, orchards and coconut and rubber plantations
(Table 1).
Table 1. Previous land use before shrimp farm development in the south of Thailand
Previous land use Percent of farms
surveyed
Rice fields 49.0
Fruit, vegetable or other agriculture 27.5
Mangrove / Wetland 13.7
Uncultivated land / Wasteland 5.9
Extensive shrimp farms 3.9
(Source: Funge-Smith and Stewart, 1996)
The mangrove forests cover about 936 km or 36% of the 2 600 km long coast of Thailand.
About 75-80% of the mangrove forest is situated on the west coast along the Andaman sea.
Mangrove forests are situated in all 12 provinces in the south of Thailand. In 35 years from
1961- 1996, about 50% of the mangrove forest was destroyed in the country (Platong, 1998).
The main causes for the destruction are conversion to shrimp farms, mining, forestry and
agriculture. About 30% of the mangrove destruction is due to shrimp farming (Tookwinas,

pers. comm., 2001).
About 95% of all shrimp farmers in Thailand today are operating intensive systems, only a
few extensive farms are left and nearly no semi-intensive farms exist. Today, there are 95%
coastal farms and 5% inland shrimp farms in Thailand (Tookwinas, pers. comm., 2001). Even
though there is a ban against inland shrimp farming, the farming method is predicted to grow
in the future (Enright, pers. comm., 2001). Most of the intensive shrimp farms are semi-closed
and only a few farmers still use open systems (Tookwinas, pers. comm., 2001).
It has been estimated, and made a national policy in Thailand, that shrimp farming areas
should not exceed 76 000 ha. The only legal possibility to establish new farms in Thailand
today is to reuse old, abandoned shrimp ponds (Tookwinas, unpublished). During 1993 there
were 72 000 ha of shrimp ponds in Thailand (Patmasiriwat et al., 1998). Only about 60% of
the shrimp farms in Thailand are registered at present, the remainder of the ponds are illegal
(Tookwinas, pers. comm., 2001). The regulations for shrimp farming are often ignored. About
80% of the shrimp farms in Thailand are small family-owned farms where the farming area is
between 0.16-1.6 ha (Tookwinas and Thanomkiat, unpublished). The average farm size in
Thailand is 2 ha according to Mr. Tookwinas. Most farms in Thailand are independent, only
1% of the farms tend to be contracted by larger companies (Tookwinas, pers. comm., 2001).
15
Most of the hatcheries are also small and family-owned. These so-called backyard hatcheries
stand for more than 80% of the national shrimp fry (Tookwinas, 1995). The hatcheries depend
on wild spawners from the Andaman sea, since a reliable cultivated source of Penaeus
monodon broodstock has not yet been developed in Thailand (Flaherty et al., 2000).
About 70% of the shrimps produced in Thailand are cultivated and the rest are trawled
(Tookwinas pers. comm., 2001). According to Sida, the majority of the coral reefs in the Thai
Gulf are destroyed at the present time (Sida, 1997). The destruction of corals is not only due
to trawling but also due to the discharge of wastewater from communities and industrial
plants, pollution from aquaculture and due to incorrect fishery gear like explosives and
poisons for fishing. Other activities damaging the coral reefs are tourist boats using the reefs
for anchorage and breaking the corals for souvenirs.
Approximately 90% of the cultivated shrimp are exported (Tookwinas, pers. comm., 2001).

Cultivated shrimp is the third biggest export by value in Thailand. In 1999, over 2 billion US$
were generated from the Black tiger shrimp industry in Thailand and the country had an
annual production of about 200 000 tonnes (The Nation, 2001; Gregow and Zetterström,
2000). The biggest importers of Thai shrimp are USA, Japan, the European countries, Taiwan
and Canada. Last year (2000) the USA imported 114 727 tons, which is about one-third of the
total import of shrimp. The EU-countries only imported 15 519 tons of Thai shrimp in year
2000. This low figure is mainly due to the increase in import tariffs following the loss of
Thailand’s status under the Generalized System of Preferences (GSP). According to the GSP,
less-developed countries have the benefit of having lower tariffs. When the less-developed
countries share of the EU market reaches a certain level it loses this benefit. The amount of
Thai shrimp imported to the EU has declined by 60% since the GSP privileges from 18 Thai
products were removed in 1999. EU import tariffs on Thai shrimp are nearly four times higher
than on shrimp from countries such as Ecuador, Colombia and Peru, which face a much lower
import tax (Bangkok Post, 2001). In year 1998, 375 tons of Black tiger shrimp were imported
to Sweden (Gräslund, pers. comm., 2001). The Swedish Society for Nature Conservation has
requested for a boycott against Black tiger shrimp (Dagens Nyheter, 2000).
Chemicals and drugs are widely used in shrimp culture for prevention or treatment of
diseases, to be used as disinfectants and pesticides, or for soil and water treatment. The use of
chemicals and antibiotics has decreased during recent years according to Tookwinas (pers.
comm., 2001). Intensive shrimp farming has introduced a wide variety of side industries at
different stages of the shrimp production: feed and chemical manufacturing industries,
hatcheries, cold-storage factories, processing industries and exporters (Huitric et al., 2000).
Today, approximately 2 million people are employed in the shrimp farming industry
(Tookwinas, pers. comm., 2001). Depending on the farm size, farmers are sometimes hired to
manage the ponds. These workers often live and work at the farms.
16
6. Environmental settings
6.1 Black tiger shrimp (Penaeus monodon)
The Black tiger shrimp (or Giant tiger shrimp) is named for its huge size and banded tail and
it dominates the production everywhere in Asia except in Japan and China (Rosenberry,

2001). The shrimps are generally found from near shore shallow waters to as far as 100 km
off shore at depths greater than 100 m (ASCC News, 1996). It accounts for more than half of
the total output of world shrimp aquaculture. The black tiger shrimp is the largest and fastest
growing farmed shrimp. It can reach a size of 360 mm and weight over 150 g. The shrimp can
tolerate a wide range of salinities, but is highly susceptible to two of the most lethal shrimp
viruses: Yellow Head Disease (YHD) and White Spot Disease (WSD). There are often
shortages of wild broodstock and captive breeding is difficult. The black tiger shrimp is a very
popular luxury food in Japan, USA and Europe (Rönnbäck, 2001).
6.2 The natural cycle of shrimp development
In the wild, shrimps mate in the open sea. After 15 to 20 days the females spawn
approximately 500 000 to one million eggs directly into the sea. The larva develops through
12 stages of nauplius, protozoa and mysis before metamorphosing into a post-larva (Figure 2).
In these stages of rapid growth, the shrimps migrate from the open sea to the estuaries. When
the shrimp has reached the post-larval stage it enters the estuaries, seeking for shallower,
often less saline waters where it can find abundant food. In the nutrient-rich mangrove forest
the shrimps develop into juveniles. They later return to the sea once again for mating. The
natural life span of black tiger shrimp is normally 1-1.5 years, whereas they reach sexual
maturity in about 10 months (Tobey et al., 1998).
Figure 2. The life cycle of the Black tiger shrimp (ASCC, 1996)
6.3 The mangrove forest
The mangrove forests are found along sheltered tropical and subtropical shorelines of Africa,
Australia, Asia, and America and act as barriers between land and sea. Mangrove forests are
comprised of taxonomically diverse halophytes (salt-tolerant plant species), which grow in the
inter-tidal zones of the tropics. Mangrove trees have adapted aerial, salt-filtering roots and
salt-excreting leaves that allow them to cope with the saline environment in the wetlands
where other plant species cannot survive (Figure 3). Mangroves vary in height according to
17
species and environment, from mere shrubs to 40 m high trees. Certain plant species occupy
particular areas, or niches, within the ecosystem at various distances from the sea. The
composition of species occurring in a zone depends on how often the zone is covered by the

tide, how salty the soil is and how much fresh water that is available (Platong, 1998).
Figure 3. Mangrove roots.
In Chapter 8 the values of the mangrove forest and the impacts of the destruction of the
mangroves are described in greater detail. In short, the values of the mangrove forest can be
summarised as follows. The mangrove forest:
• provides nutrients for the marine environment and supports complex food webs.
• creates breeding habitats and restrictive impounds that can offer protection for maturing
offspring.
• supports other ecosystems like mudflats, sea grass beds and coral reefs.
• filters nutrients and traps pollutants and thereby improves the water quality.
• protects the coastal areas from erosion, storm damage, and heavy winds by stabilising the
sediments.
• has a high conservation value because of its huge biodiversity.
• has a high potential value due to the vast genetic resources that can be found there and can
be used in the production of drugs and chemicals.
• supplies the coastal communities with food, medicines, fuel wood and construction
materials (table, appendix 3).
• provides many commercially important products (table, appendix 3) like charcoal, paper,
textile, leather, tannins and seafood.
Mangrove forests are among the most threatened habitats in the world and are disappearing at
an accelerating rate. The forests are suffering from pollutants, attacks by parasites and
prolonged flooding from artificial dikes, etc. In addition, the charcoal and timber industries as
well as urbanization, agriculture, aquaculture and tourism have severely impacted mangrove
forests. Also over-exploitation by traditional users and mining, whose dominant effect is
deposition of sediments, have greatly affected the mangrove forest. The rapidly expanding
shrimp aquaculture industry is today a great threat to the mangroves both through
deforestation and through sedimentation and pollution from the waste water from the ponds.
Globally, shrimp farming may be responsible for between 10 and 25% of the mangrove
clearing since 1960 (Tobey et al., 1998) and in Thailand for about 30% (Tookwinas, pers.
comm., 2001).

18
Traditionally, shrimp farming was initiated in mangrove areas. These extensive farms
depended on the tide to bring in seed and feed into the pond. It is today recognized that
mangroves are unsuitable for semi-intensive and intensive ponds because of the acid sulfate
soils (Tobey et al., 1998). Additionally, the mangrove soil is very soft and contains plenty of
roots and stumps and consequently is not suitable for pond construction.
According to Plathong (1998), the dramatic decrease in mangrove forest in southern Thailand
has been attributed mainly to conversion to shrimp farming. Mangroves along the east coast
of southern Thailand have, though, been converted for various land-uses such as salt ponds,
shrimp ponds, coconut plantations, paddy fields or buildings. According to John Hambrey
(The Mangrove Questions), Funge-Smith (pers. comm., 2001), and others, shrimp farming is
only one of many pressures on the mangrove and rarely the most significant. There is
confusion concerning the definition of mangrove because different countries use different
definitions. Should the non-flooded secondary forest behind the mangrove forest be defined as
a mangrove? To date most intensive shrimp farm developments have taken place in this non-
flooded area or in salt marshes. In contrast, extensive shrimp ponds are typically built in the
flooded parts of the mangrove. Figures blaming the shrimp industry for the destruction of
about 30% of the mangrove forest in Thailand often refer to this secondary forest behind the
primary mangrove. Additionally, pristine mangrove forests are very rarely destroyed in
Thailand at the present time. Most of the mangrove in Thailand today is young because of
intense charcoal harvesting some decades ago and therefore the conservation value of this
young forest is questionable (Funge-Smith, pers. comm., 2001).
6.4 Hatcheries
To cope with the high demand for post-larvae in Thailand, hatcheries have become a great
industry in the country. Actually, all post-larvae in Thailand are hatchery-produced from wild
broodstock (Funge-Smith and Stewart, 1996). This causes high pressure on the fishing for
these wild shrimp. The hatcheries sell two types of products: nauplii (tiny, newly hatched first
stage larvae) and post-larvae. Nauplii are sold to specialists who grow them to the post-larval
stage. Post-larvae are stocked in nursery ponds or directly in grow-out ponds.
Gravid shrimp are either captured in the wild or matured in the hatchery. The shrimp spawn in

the dark, so through photoperiod manipulation they can be induced to spawn at any time. Eye
ablation (cutting off one eye from the female) to initiate spawning in the female shrimp is
common in Thailand today. This results, however, in a rapid death for the shrimp and thereby
this method is less sustainable than the one for pond-reared brood stock (Funge-Smith and
Stewart, 1996). One day after spawning the eggs hatch into nauplii. These metamorphose into
zoeae after a couple of days and then into myses, which is the third and final larval stage. This
stage lasts another three or four days and then the myses metamorphose into post-larvae. Post-
larvae look like small adult shrimps and feed on zooplankton, detritus and commercial feeds.
The entire process from hatched eggs to post-larvae lasts approximately 18 - 20 days
(Rosenberry, 2001).
Post-larvae may be placed in nursery ponds where they are cultured for 30 - 45 days before
being placed in grow-out ponds. The grow-out ponds are the only ponds that can produce
harvest-sized shrimp. Therefore these ponds should be cycled as frequently as possible during
the growing season. This is facilitated by the use of nursery ponds. This technique is called
"staging" and facilitates the feeding and counting of the shrimp (Tobey et al., 1998).
19
6.5 Grow-out techniques
The long coast line of Thailand and the tropical climate provide ideal conditions for year-
round shrimp culture. Marine shrimp farming systems can be classified into three categories
of intensity: extensive (traditional), semi-intensive and intensive farming systems. The
different types are classified in terms of cultured area and stocking density.
Extensive culture
The extensive shrimp farming system is primarily used by farmers in areas with limited
infrastructure, few trained aquaculture specialists, inexpensive land and high interest rates.
The ponds are located along bays and tidal rivers and are constructed by the accumulation of
elevated mud walls around the bottom of the ponds. The trapped larvae are prevented from
returning to the sea with the withdrawal of the tide by a screen placed in the sluice of the wall.
When local waters are known to have high densities of young shrimp, the farmer opens the
gates of the pond, captures the wild shrimp and grows them to market size (Tobey et al.,
1998).

Several species coexist together in the pond and producers rely on the tide for water exchange
(0-5% water exchange per day) and to bring in seed and food (Rosenberry, 2001). Survival
and yield are low in extensive culture, as are costs and risk. The density of shrimp is 2 – 5
shrimp per m
2
(Dierberg and Kiattisimkul, 1996) in traditional farming and the ponds are
large (5-10 ha). The farms have few inputs and are mostly family-owned. Extensive pond
enclosures have an irregular shoreline, the depth is variable but shallow and there may be a
considerable amount of vegetation left in the pond. The extensive shrimp farms are often
established in mangrove swamps or in salt flats, because the conditions for more intensive
culture are poor in these areas. In some cases, fertilisers or manure are added to promote algal
growth. Disease outbreak is rare because of the low densities. Most of the extensive farms in
southern Thailand are located in Nakhorn Sri Thammarat (Tookwinas and Thanomkiat,
unpublished).
Semi-intensive culture
Semi-intensive shrimp farms are conducted above the high tide line. The stocking densities
are higher (5 – 10 shrimp per m
2
) than the natural environment can sustain without additional
input of, for example, feed (Dierberg and Kiattisimkul, 1996). The ponds are smaller (1-6 ha)
than the ones used in extensive culture and are more regular in shape (Tookwinas and
Thanomkiat, unpublished). This leads to better control over the grow-out environment. The
ponds have dikes and are easier to harvest than the extensive farms. Nursery ponds are often
used. In semi-intensive shrimp farming, pumping systems and sometimes aerators driven by
diesel or electrical energy are used to regulate the water exchange and to bring oxygen to the
bottom of the pond. The daily water exchange rate is 0 – 25% (Rosenberry, 2001). Skilled
management and labour is needed and the farm depends on purchased feed and seed stock.
The shrimps are fed both with natural food and purchased shrimp feed. According to
Tookwinas (pers. comm., 2001), there are hardly any semi-intensive shrimp farms in Thailand
at the present time.

Intensive culture
In intensive shrimp farming the ponds varies in size from 0.16 to 1 ha (Tookwinas and
Thanomkiat, unpublished). The intensive system demands around the clock management.
There are greater inputs of operating capital, equipment, skilled labour, feed, nutrients,
20
chemicals, drugs and antibiotics. The shrimp are fed up to five times daily supplemented with
vitamins and minerals. The ponds are aerated with the use of paddle wheels. The stocking
densities are high (30 – 60 shrimp per m
2
). In intensive shrimp culture, there are 2 - 3 harvests
per year and water exchange rates can be as high as 40% daily (Dierberg and Kiattisimkul,
1996). Usually, intensive systems are coupled to their own hatcheries and nursery ponds. The
risk of disease is high and a whole crop can be lost in hours. There are different types of
intensive cultivation systems: open, semi-closed, closed and super-intensive systems.
Open intensive systems
Traditionally, water quality has been maintained in shrimp production through the use of a
high rate of water exchange to flush excess plankton and nutrients out of the pond. The open
intensive ponds require large amounts of daily water exchange to maintain suitable water
quality.
Semi-closed intensive systems
Due to increasing farm density, deteriorating influent water quality and the rise in viral
diseases, there has been increasing resistance amongst farmers to the use of high water
exchange. In semi-closed farming systems there is no water exchange during the first month
of production (except for compensation of evaporative loss) due to the high risk of disease
during this time. A limited water exchange commences during the second month of
production.
Closed intensive systems
In fully closed intensive shrimp farming there is no water exchange to the outside at all during
the whole production period. Water is only added for compensation of evaporative loss and
seepage. In most closed systems, water is discharged to the environment at harvest. Some

closed intensive farms, however, treat and recirculate the water at harvest and thus have zero
water exchange systems.
Super-intensive systems
Super-intensive shrimp farming is still in its experimental stages. It requires huge amounts of
water, around 50% daily water exchange and can produce yields of 10-100 t/ha/year
(Rönnbäck, 2001). Super-intensive production requires huge investments in technology,
equipment, staff expertise and overall management. Generally, these farms have problems
with management, diseases, crop failures, water quality, finances and the environment
(Rosenberry, 2001).
Table 2. Percentage water exchange in different shrimp production systems in southern Thailand
Percentage water exchange (% per month)
Month of
production
Open system
(clay soil)
Open system
(mangrove soil)
Semi-closed
system
Closed system
1 12 10 6 1
2 86 104 54 5
3 128 125 97 7
4 168 125 107 7
(Source: Funge-Smith, unpublished).
21
6.6 Inland shrimp farming
The establishment of low salinity shrimp farms in areas far inland from the coast has greatly
contributed to maintaining the high production of shrimp in Thailand. Low salinity shrimp
farming relies on salt water trucked in from the coast. The farms are established in

predominating rice-growing areas, 100 km or more inland from the coast (Flaherty et al.,
2000). When low salinity shrimp culture techniques developed in the nineties the shrimp
species Penaeus monodon was used for reasons of familiarity and availability. This species is
well known for its tolerance to variations in temperature and salinity. The development of low
salinity shrimp farming was dependent on the availability of suitable shrimp post-larvae that
had been acclimatized to low salinity levels (Flaherty et al., 1999).
The largest concentration of inland shrimp farms is in the lower central plain of Thailand,
where rice paddies are widespread. It is not surprising that low salinity shrimp farming
evolved in traditional rice-growing areas. In these areas there are plenty of water supplies,
which are critical to the success of shrimp farming. Additionally, the irrigation infrastructure
that was originally developed for rice cultivation is easy to adapt to shrimp farming. The
primary difference between inland and coastal farming is the salinity level in the grow-out
pond. The salinity in coastal shrimp ponds varies between 10-30 ppt and in inland shrimp
ponds between 4-10 ppt. The standard grow-out period for inland culture systems is relatively
short, 120 days. This is because the falling salinity levels, due to the continual addition of
freshwater in the ponds, have negative effects on shrimp health and development (Flaherty et
al., 2000).
The most serious impact from inland shrimp farming is salinisation of surrounding agriculture
and ground water. Recent estimates of the total land area subject to direct salinisation impacts
as a result of inland shrimp farming is 22 455 ha, according to DOF, 1998. Much of this land
was previously used for rice production and the possibility of returning to rice cultivation if
shrimp production fails in these areas is very uncertain. It is difficult to estimate the
production of shrimp from inland farming because the Department of Fisheries in Thailand
does not identify if the shrimp originates from inland or from coastal farming. However, it has
been suggested that inland low salinity cultures account for 30-40% of Thailand’s production
(Flaherty et al., 2000). Another source estimated that inland farming accounted for 40-50% of
Thailand’s cultured shrimp production (Vandergees et al., 1999). According to the DOF, only
5% of the shrimp farms in Thailand are inland farms (Tookwinas, pers. comm., 2001). These
differences in estimations are mainly due to the large number of unregistered inland shrimp
farms in Thailand today. An association of inland shrimp farmers reported that inland shrimp

farms have a total pond area of about 22 400 ha and would be able to produce approximately
100 000 tons of shrimp if the ban on inland shrimp farming is withdrawn (Asian Aquaculture
Magazine, 2000).
6.7 Production process and water treatment
The production process involves four different stages: pond preparation, stocking, culturing
and harvesting. Pond preparation normally begins immediately after harvest and may take up
to a month. After harvest the pond is cleaned of the wet mud using a tractor or a water jet.
Lime is used to sterilize the pond sediment and to reduce acidity in mangrove areas and other
chemicals are used, for example, to reduce pests. When the pond has dried out, seawater is
pumped into the pond and the zoo- and phytoplankton multiply until they reach a sufficiently
high concentration. At the second stage the shrimp post-larvae are put into the pond.