95. The following sessions considered different approaches to the environmental management of aquaculture and comprised: (i) presentation of the study overview by the Project Team followed by reviews and complementary presentations by the resource persons; (ii) working group sessions which covered environmental management options in inland and coastal aquaculture; and (iii) a general discussion. The working groups also developed a set of suggestions concerning the actions to be taken as follow-up to the workshop, including suggestions directed at governments, farmers and supporting private sector industries, and regional and international organisations. These suggestions were presented for discussion and adoption by the workshop participants.
A. Presentation of study overview
i. Environmental management aspects
96. Dr Michael Phillips made a presentation concerning the environmental management aspects of the study. It concentrated on ecological issues and the actions taken by farmers to manage environmental impacts related to aquaculture. The presentation described the concepts of environmental management of aquaculture, rather than detailed discussion of the various environmental problems which had already been illustrated in the country statements. Dr. Phillips emphasised that aquaculture is part of the natural environment. The resources required and used by aquaculturists include mainly land, water, feed and seed, as well as some other inputs. Aquaculture is highly dependant both on the quality and quantity of the resources available and, because these natural resources are often used by other people (non-aquaculturists), there is potential for conflict over access to resources. The quality of these resources may also be adversely affected by these competing uses. Such problems arise particularly where resource use pressures are high, e.g. where population densities are high, or where aquaculture units use a high proportion of the available resource. As aquaculture is part of the whole natural resource system, the “ideal” environmental management of aquaculture should consider both on-farm and off-farm management of resources.
97. The environmental impacts related to aquaculture development may be neutral, positive or negative. Small-scale, integrated aquaculture-agriculture farms were considered likely to be environmentally neutral, however, even with these systems considerations over the alternative use of water, land, fertilisers and seed may exist. There were also many examples of positive environmental impacts. Examples included the use of fish ponds to protect wetlands in Hong Kong, some sewage fed fish culture systems, and the use of cage culture of filter feeding fish which in Singapore had been used to clean up eutrophic reservoirs. It was also emphasised that the United Nations Conference on Environment and Development (UNCED) had recognised the potential role of freshwater fisheries and aquaculture as an environmentally sound use of freshwater resources.
98. The negative environmental impacts included impacts on aquaculture, of aquaculture and of aquaculture on aquaculture. The impacts on aquaculture included habitat destruction, water pollution and red tides, leading to losses of seed supply and some severe economic losses, particularly in coastal environments. Impacts of aquaculture included loss of wetlands, including mangroves, land and water use conflicts, water quality changes due to pond effluent discharge and introductions of exotic species causing loss of biodiversity in aquatic ecosystems. Aquaculture operations have, in a number of cases, severely affected their own culture environments through self-pollution. There are examples where self-pollution has resulted in severe economic losses to countries of the region.
99. The presentation then considered the different factors affecting the potential for environmental impact. These included: (i) the type of aquaculture system; (ii) the degree of intensification; (iii) species characteristics; (iv) location and site factors; and (v) operational and farm management practices. The introduction of aquatic species was also an important aspect. This discussion then led to farmer-level management possibilities that exist for improved environmental management of aquaculture at farm level. These environmental management “options” were considered to be: (i) “closed cycle” systems, e.g. integrated aquaculture-aquaculture or aquaculture-agriculture farming systems; (ii) selection of species, e.g. well adapated, indigenous species; (iii) balancing culture intensity with the capacity of the culture unit and the culture environment; (iv) selection of suitable sites; (v) design features; and (vi) operational methods, including feeding strategies, seed supplies, and the environmentally sound use of chemicals and drugs.
100. It was emphasised that actions by individual farmers may not be enough and that co-operative action may be necessary where farmers are sharing common resources. Inadequate management of common water resources has led to self-pollution and serious disease outbreaks and some co-operative sharing of responsibilities in water management was considered important. Several examples of cooperative action by shrimp farmers were noted, including water management co-operation and shrimp farm estates, where farmers could share a central water supply and drainage system.
101. In concluding the presentation, the question was posed as to whether farm actions were sufficient for environmental management of aquaculture. As many of the problems arising involve other sectors, some integrated management involving co-operation among different users was probably necessary. As some of the resources were also often considered common property, e.g. water, then it was also likely that some form of public sector management would be necessary in addition to farm-level management.
The overview presentation of environmental aspects of aquaculture appears as Annex III-1.
102. Dr. Somsak Boromthanarat, resource person on environmental aspects, made a presentation on coastal zone management. There is vast potential to develop coastal resources for aquaculture in coastal Asian countries. As a high demand exists for shrimp farming opportunities, there is always a need for more supplies and resources. With appropriate natural resources and environment in the coastal zone, the culture of Penaeus monodon appeared to be a new alternative for resource use. Shrimp culture deals with the integration of many natural resources (including land and water), however, it has also created many external impacts to the environment, natural resources and human society. The presentation provided an overview of some of the lessons learnt from the present condition of shrimp farming development in Thailand.
103. The problems related to shrimp culture expansion in the region were described as water-related problems (i.e. water pollution) and land related problems, particularly those related to conversion of mangroves and agricultural land. The following problems can be considered to be those of a country's regional development: land use planning and related law enforcement. The uncontrolled extension of the shrimp farm area, the cutting of the mangroves, the associated water demands and water quality problems, as well as land contamination, demand a well balanced choice in the utilisation of land resources. The technology and profit driven nature of the industry, as well as its vulnerability, also tends to lead farmers towards little consideration of environmental issues.
104. The coastal zone management problem mainly refers to the use of coastal land and water resources. This refers to the imbalance in land use, i.e., the rapid changes from agriculture to shrimp farming with associated land degradation and water pollution. In addition, at some places along the coast in Thailand, huge sea water intake installations have been constructed, consisting of large pumping stations and supply canals built on sizeable jetties. These structures cause substantial local sedimentation and erosion, as they disturb the coastal equilibrium of the northwards current that is directed along shore and this acts to transport sediment. Most of the environmental problems related to the present development within the coastal basin include land degradation, water pollution, the destruction of environmentally valuable wetlands and mangrove forests, and the disturbance of the present coastal equilibrium.
105. Institutional problems observed in the coastal area include the lack of an authority responsible for integrated regional planning. Various Thai Government authorities like the Irrigation Department, the Rural Water Authority, the Tourism Authority, the Public Works Department, the Forestry Department, etc., bear responsibility for development within the field of their own technical competence. However, regional objectives and targets regarding land and water resources utilisation, coastal zone management, industrial development, and others, should first be formulated by a competent planning authority. Tasks and responsibilities of the individual authorities seem narrowly defined and wherever regulations do exist, law enforcement is lacking. An example is the uncontrolled change of land use from agriculture to shrimp farms and the destruction of wetlands and mangrove forests for the same purpose.
106. In conclusion, the critical issues and problems in the coastal area are centred around the conflicts between economic activities and the ecosystem. Resulting problems include pollution of surface waters, degradation of the mangrove area and wetlands, and threat of storms, typhoons and flooding. The issues regarding shrimp farming development are the extensive exploitation and destruction of natural resources. In order to achieve sustainable development in the planning and implementation of the development of a shrimp farm culture system for a given coastal region, it is necessary to take an integrated approach to the economic, natural, and social environments of the region. However, the rapid socio-economic, aquaculture and ecological changes require immediate, firm decisions and short-term action on a number of potential projects and measures that may improve and/or solve the common problems that face shrimp farm developments. It is also necessary to have a flexible plan and decision-making apparatus because this situation is in constant change. This quick-response action will not hinder long term planning.
107. Quick response actions include:
The implementation of an integrated water management system for shrimp farming, consisting of a centralised system of freshwater and salt water supply, to prevent coastal erosion by the individual salt water inlet structures. Design of a separate collector drain to which all shrimp ponds are connected for the discharge of waste water;
A taxation system and charges for water use and waste water disposal;
The initiation of the on-site treatment of waste water from shrimp farms;
The development and formulation of a sound master plan for conservation of mangroves and wetlands and a realistic management plan for the mountain forest area left;
The creation of an eco-tax on land degradation;
The creation of land use zoning and the encouragement of agricultural diversification;
The installation of flood damage reduction measures, flood warning systems, and evacuation procedures.
The review paper on coastal zone management appears as Annex III-2.
108. Discussion on the environmental aspects. The workshop discussed the concepts of “carrying capacity”, “holding capacity” and “environmental capacity”. There was a need to clarify some of the terminology in use. However, it was clear from discussions that it was generally undesirable for aquaculture farms to exceed the “capacity” of the environment where farms were located. It was noted that there were many examples where over-investment in shrimp ponds in coastal areas, large densities of cages and pens in areas with limited water exchange and large areas of mollusc culture had led to growth reduction, poor productivity in culture units and, in some cases, catastrophic losses due to disease outbreaks. It was generally recognised that an understanding of the factors involved in determining the capacity of coastal and inland environments would be useful as a planning tool. There was a particular need to develop more refined methods for assessing the capacity of coastal environments.
109. The importance of proper environmental impact assessment (EIA) for major aquaculture developments was also stressed by the Asian Wetland Bureau representative, including proper valuation of wetland environments, particularly with respect to economic costing of both goods and services. The representative recommended further strengthening of EIA procedures for wetlands.
110. Dr. Paul H. M. Guo, the representative of the World Health Organization (WHO), gave a short presentation on the public health aspects of aquaculture. Dr. Guo said that while aquaculture has benefited many people in providing food and job opportunities, it has created negative impacts as well on humans and the environment. In aquaculture activities, human diseases could be transmitted through: (i) pathogens in contaminated water or fish tissue; (ii) intermediate hosts such as snails or fish; (iii) vectors; and (iv) veterinary drugs. Viral, bacterial or protozoan pathogens could infect consumers, fish handlers and aquaculturists. Consumption of raw or partially cooked aquatic fauna or flora could pose potential health problems, such as schistosomiasis and clonorchiasis. Finfish, crustacea or mollusca harvested from polluted waters could contain toxic organic compounds such as PCB and pesticides, or inorganic substances such as mercury and cadmium, which may cause food poisoning or cancer in consumers. There are various kinds of public health problems associated with aquaculture development. Dr. Guo's presentation elaborated on the route of disease transmission, the life cycle of Schistosoma and Clonorchis and measures to control various infections. The guidelines formulated by WHO to reduce/eliminate the health risks from aquaculture and agricultural activities were briefly described. The WHO representative thanked the organisers for the invitation to attend the meeting, the subject of which was very much within the interests of WHO and looked forward to developing a closer future co-operation in topics of mutual interest.
The presentation on public health aspects of aquaculture appears as Annex III-3.
111. Discussion. Reference was made to the fact that codes of practice governing aquaculture products had been drafted recently by the Codex Alimentarius, which could be made available to the participants. The discussion further emphasised that public health concerns were important and should be given due consideration at both national and regional levels in supporting aquaculturists to produce a safe and marketable product.
112. Mr. Daniel Fegan, Aquastar Laboratories outlined various points of concern to the private sector. Mr. Fegan described the Aquastar system of shrimp farming. The company was based in the southern part of Thailand and was a vertically integrated industry with 750 ha of shrimp ponds coming under operation this year. The shrimp farmers co-operating with Aquastar were owners of their land and were under contract for 15–25 years. Aquastar provided assistance with infrastructure and also sold inputs (water, seed and feed) and bought shrimp from farmers. He emphasised that an objective of the company was long-term sustainable shrimp farming and that environmental issues were of concern to the company. In particular, it was important to maintain environmental quality in ponds and water supplies to avoid shrimp disease problems. In practical terms, this meant siting water intakes offshore, good design of water supply and drainage systems, reduced stocking densities (with production yields of 6t/ha/crop) and careful attention to stocking and feeding practices. Mr. Fegan acknowledged that there were difficulties in instilling environmental awareness in farmers, as many were tempted to push the biological limits of their culture ponds to obtain maximum profits in short periods of time. He emphasised that there was a very strong need to instil greater awareness of environmental issues into shrimp farmers.
113. He strongly recommended the formation of farmer groups which had great advantages in terms of solving common problems. He described a shrimp farmer group in Surat Thani where small-scale shrimp farmers had grouped together to co-operate on water management. The co-operation had helped reduce some of the water pollution and shrimp disease problems. Farmer groups were also a good route for dissemination of information and education and were to be recommended.
114. There followed some discussion of sustainable yields possible from shrimp ponds. The experience of Aquastar was that pond yields of greater than 6t/ha/crop were not sustainable over the long term. Farmers were encouraged to partially harvest to maximise yields from ponds. Aeration was another important aspect. Figures from research work in the USA suggest 500–600 kg of shrimp/hp of aeration was appropriate. He suggested further research work was necessary on the sustainable yields from shrimp ponds. In relation to research he also mentioned that it was important to work with farmers, and that farmers were extremely innovative in dealing with problems. Research should aim to work with and build on such innovation. He also suggested that any research work or regulatory frameworks should try to build a framework within which farmers could deal with their own problems.
115. In further discussion, Mr Fegan recommended governments and the private sector to consider an accreditation scheme for consultants, to avoid bad consulting practices. He suggested a database of good consultants may be taken up by NACA, FAO or governments.
116. Mr. Fegan mentioned among the negative impacts of shrimp culture on the environment as subsidence of land due to groundwater pumping, flooding of agricultural land by saltwater pumping and blockage of drainage culverts by water supply pipes. He expressed concern about the effects of the substantial movement of shrimp on genetic diversity of native populations, as well as disease transfer. He said that much could be done by the industry itself to improve farming practices, but government cooperation was also necessary. There was a need for better trained graduates and information and education was necessary for farmers.
The presentation of the private sector participant (Aquastar Laboratories) appears as Annex III-4.
117. Discussion. The government representatives requested further information on different aspects of the presentation. The need for governments and farmers to co-operate in joint research was mentioned, as was the need for governments to work closely with farmers in identifying and solving problems. Mr Fegan further mentioned that large industrial concerns involved in shrimp farming in Thailand were willing to sponsor research work and were considering, with the government, establishing a shrimp research centre. Mr Fegan elaborated on the causes of the various “crashes” in farms which were a worrying feature of shrimp farming. He indicated that bad site selection was a major factor, in particular farms on estuarine environments faced high risks from water pollution. He suggested that open ocean systems, using full strength seawater were more successful, because of the generally better quality seawater in such environments. The original perception that Penaeus monodon required brackishwater was proving incorrect, as profitable farming was perfectly feasible on full strength seawater (albeit with a slightly slower growth of shrimp, 2–3 weeks extra required per crop). Poor management skills were also considered a major cause of hatchery and pond failures.
118. Dr. Arun Jhingran, the inland aquaculture resource person, presented further elaboration of the environmental constraints associated with enhanced fisheries. These were elaborated as:
119. Culture based fisheries, or enhanced fisheries, in lakes and reservoirs are vulnerable to all the negative environmental impacts common to closed aquaculture systems. In addition, they are also subject to those natural and man-induced stresses which are inherent to open water systems. The biological production functions and fish harvests from these multi-use water bodies are impacted by: over abstraction of water; high sedimentation rates; pollution from urban and industrial discharges and agricultural run-off; introduction of exotics; transfer of pathogens; parasites and diseases; hypernutrification and eutrophication through organic fallout from fish cages; impairment of aesthetic qualities; and disruption of the life cycles of resident and migratory fish stocks.
120. The enormity and diversity of these ecosystems demand a separate approach towards their fisheries management which involves complex socio-economic, legal, biological and environmental variables. Furthermore, these ecosystems portray unique features of limnological, environmental and production dynamics. Fisheries management in such multi-purpose aquatic resources has to be viewed today in the wider context of aquatic resource management, consistent with ecosystem changes and competing resource use.
121. Aquaculture and fisheries enhancement in lakes and reservoirs are at a critical point in their development. The degradation and loss of fisheries habitats are increasing and a change in management policy issues is imperative for the sustainable development of their fisheries. Development strategies need to have a holistic approach suited to the entire basin. There is a need for a systems approach which will ensure a basin-wide perspective towards development and management. This would enable adjustment and abatement of those parameters which receive impacts. In such an integrated development of multi-use systems, it should be possible to develop all living resources together. Thus, a system which links the management of fisheries, forestry, agriculture and aquaculture to agro-industrial and hydro-electric units will facilitate recycling of nutrients, optimise river basin production and minimise pollution, eutrophication and contamination of the environment consequent to changes in the hydro-biological and socio-cultural regime.
The presentation on aquaculture and enhanced fisheries in inland water bodies appears as Annex III-5.
122. Discussion. The discussion that followed concentrated on the issue of introduction of exotic fish species. It was emphasised that fish did not respect national borders when countries shared common water resources, e.g. in the case of the Ganges river system. In such situations, introductions of exotic fish in one country may adversely affect aquatic ecosystems in other countries. It was mentioned that it was difficult to control the private sector, even where regulations had been in existence. However, efforts were warranted to strengthen national action to control indiscriminate introductions.
123. There was a great deal of discussion concerning the tilapia. The experience in India was that during the early stages following introduction, growth performance had been good, but after some time results were poor. The meeting expressed concern about the widespread dissemination of tilapia throughout the region, and requested that further information be obtained on this subject, as the basis for formulating further advice to governments. Other examples were given of both positive and negative impacts associated with introductions of silver carp in India.
124. The regional aquaculture officer of FAO pointed out that the question of biodiversity was an important one. There were already existing codes of conduct, e.g. developed by EIFAC and ICES, which were available to regulate introductions (and transfers) of aquatic species. In some cases, such codes had been adopted by countries. He also pointed out that aquaculture could have positive impacts through conserving biodiversity. Examples were given of the giant Mekong catfish and arowana fish stocks, which were being conserved through artificial breeding.
125. In view of the negative and positive aspects associated with exotic fish species, and the potential serious repercussions for native fish stocks, the meeting considered that further information should be collated on the topic, including special “case studies” to provide governments with further advice on this issue. It was also emphasised that there was a need to enhance awareness and concerns over such issues as public participation in controlling risks was essential. It was further mentioned that it would be useful to catalogue in some way fish genetic resources, as a basis for conservation efforts, reference being made to the Centre for Fish Genetic Resources in India which had recently completed this task.
ii. Legal aspects
126. A. Van Houtte presented the fundamental techniques of environmental and aquaculture law. Ms Van Houtte reviewed the situations that give rise to legal issues for the region, as follows:
Aquaculture development is intrinsically dependant on water quality and quantity;
A balance needs to be found between the continuation of existing farm activities and the conservation of existing natural resources;
There is great concern about water and land (often coastal) availability, in terms of competing water/land uses;
Aquaculture involves production from (usually) publicly regulated resources i.e. that the public most often holds or manages directly or indirectly (water, coastal land, foreshore, wetland, etc.);
Concerns about the necessity of producing a commodity ready for consumption in the domestic or foreign market.
127. Following this brief introduction, she dealt with the legal framework for control of the environmental impacts on aquaculture and for control of those caused by aquaculture. With regard to the first subject, she described the various techniques which have been developed to apply the basic principles of environmental law i.e. conservation, amelioration, precaution and prevention, protection and polluter pays. The techniques which could protect aquaculture from environmental damage, include:
Preventive measures. These imply that environmental harm can be predicted through the usual operations of an activity or of a product. Further, they also aim at mitigating and preventing damage in the case of accidental pollution. They may include licensing techniques, EIA procedures and regulatory rules, i.e. standard setting and restrictions and prohibitions;
Enforcement measures. A law must be enforceable and despite the preventive measures, environmental damage occurs sometimes through intentional or negligent conduct, or sometimes accidentally. To address this, there are enforcement measures which may include civil actions, administrative remedies and criminal prosecutions;
Economic incentives or disincentives for environmental protection. These are intended to affect human conduct towards the environment. They may include effluent charges, user charges, product charges, exemption fees, low interest loans, deposit schemes and negotiable permits. Some of these instruments are pure incentives to affect behaviour while others are revenue generating to finance policies.
128. Following the presentation on the various techniques of environmental law, Ms. Van Houtte gave a summary of the basic components of aquaculture legislation. The reason for elaborating an aquaculture specific set of rules may be found in the fact that aquaculture, being increasingly a specialised activity, deserves a specialised law. However, aquaculture as a legitimate user of natural resources will unavoidably be subject to general environment-related legislation. As such, a specific aquaculture-related legislative instrument may provide for an authorisation procedure allowing for control of installations and operations, location and pollution. It may, in addition, impose an EIA requirement preferably set in relation to the scale of proposed development and perceived sensitivity of the recipient body, and trading and taking restrictions e.g. restrictions on the use of hazardous substances, limits for the purposes of seed collection, or restrictions on introduction of species. In view of its enforcement and implementation, such aquaculture specific laws may use the following techniques: fiscal incentives (e.g. differential financial government loans to direct the developer towards desired sites, charges for access to water resources based on the use of the water resources or on the impact on water quality); and regulatory monitoring and administrative procedures (e.g. for the purpose of protecting the environment an authorisation may be refused, not renewed, varied or withdrawn).
129. Driving forces with respect to the scope of such legislation, i.e. the persons subject to it and the areas to which it applies, are: (i) the purposes of the industry (food production and market, employment, research or recreation); (ii) the resources used (water, land, species, feeds, energy, labour, etc.); (iii) the system or methods used for production; (iv) the environment in which the production is conducted; and (v) the technical capacity of the government to implement and enforce the measures.
130. Ms. Van Houtte summed up her presentation with a brief note on the institutional framework for aquaculture. She identified the following major problem areas: (i) the control of environmental impacts of aquaculture has not always an institutional identity; (ii) as aquaculture is touching upon various natural resources, an environmental management plan for aquaculture must necessarily involve co-ordinated action concerning different matters in areas already included within the spheres of authority of many agencies; and (iii) the division of functions between the central management agency and the various less centralised institutions and authorities are, although of critical importance, not always clear.
131. She encouraged the participants to consider the following questions:
How can integrated management be fostered? As a preventative measure, for instance, a single authorisation system or EIA procedure, or as a curative measure?
Centralised versus decentralised structure? The use of local authority structures may have benefits:
However, benefits of a centralised approach relate to:
fragmentation of efforts are avoided as well as inconsistent application of policies and other disjointed results.
Is there need for a single government unit to administer the aquaculture sector in an integrated manner?
132. To conclude she gave a few suggestions on how to prepare and elaborate an appropriate set of rules to ensure that aquaculture is appropriately regulated and that the legal rights and duties are clearly defined and enforced.
The presentation on the legal and institutional aspects appears as Annex III-6.
133. William Howarth, resource person on legal aspects, presented the essentials of aquaculture law. He commenced with the observation that the concern of the Workshop was to a large extent an exercise in practical environmental law making: how best to administer and regulate an important and growing industry in the best interests of all involved and how to secure an adequate level of environmental protection in accordance with the principle of sustainable development. The prescience of environmental problems was not always matched by action and, though there is a moral imperative to maintain the environmental quality of the earth, this is not always followed in actual behaviour.
134. Whilst laws are needed to compel environmentally acceptable action, workable environmental laws must conform to three criteria: they must be appropriate; practicable; and enforceable. The requirement of appropriateness means that they must be based upon the best scientific evaluation of the problem, taking a precautionary view of the risks involved. The need for practicability means that whatever law is enacted must be readily understood by those to whom it applies and those who must administer it. The quality of enforceability means that resources should be available, or made available, to ensure that the law will be effectively applied and not fall into abuse. In relation to environmental laws governing aquaculture, the main principles were set out in Professor Howarth's written paper and were broadly in conformity with the recommendations of the TCP Report. Codification of aquaculture legislation in a single enactment is highly desirable, and the need for an integrated licensing system administrated by a specialised agency has considerable advantages in avoiding the need for multiple consent applications. However, not all countries have the same needs for aquaculture regulation and it is sometimes unwise to be too stringent in approaching this matter.
135. It appeared from the country reviews that those nations with the most highly developed and intensified aquaculture industries suffer the most serious environmental problems. Indeed, it might be speculated that there was a law of “diminishing returns” in operation. Significantly, the most developed aquaculture nations tend to have the most stringent environmental laws as a consequence. Hence, where aquaculture is less well developed it may not invariably be necessary to enact such elaborate legislation, providing always that the need for a precautionary approach is kept uppermost in mind.
136. The ultimate exercise is one of preparing an environmental law “shopping list” and, as with many shopping lists, there are not always enough funds to buy everything we might like. It is, accordingly, necessary to make the list but for the purchaser to pick out the priorities for purchase on the basis of the resources that are available. Model lawmaking serves a purpose but all legislators must be wary of the danger of “biting off more than they can chew”.
137. He expressed the hope that the “guidelines” that were envisaged as the end product of the workshop would reflect these points, and that any subsequent lawmaking that they prompted would take account of the requirements of appropriateness, practicability and enforceability in the light of the particular circumstances existing in the nation to which they applied.
The review of legal aspects “Essential of Aquaculture Regulation” appears as Annex III-7.
138. Discussion on the legal aspects. Following the presentation of the legal framework governing the environmental management of aquaculture in the Asian region by A. Van Houtte and W. Howarth's views on aquaculture legislation, the participants extensively discussed the contents of definitions of the term “aquaculture”. It was recognised that there are many possible definitions depending on the purpose of the envisaged law or regulation. For example, the definition adopted by FAO for statistical purposes aims at the distinction of aquaculture from capture fisheries. The term “aquaculture” involves a human intervention in the production process and ownership of the stock. Consequently, it does not include enhanced culture-based fisheries where the stock becomes an open access resource. Its purpose is to facilitate collection of statistical data. It was mentioned that the distinction of aquaculture and culture-based fisheries is not so useful in some cases, for example, in reservoirs. Definitions given in laws should reflect the purposes of those laws, and should facilitate their implementation and enforcement. Aquaculture could be defined in general terms or refer only to a specific culture system or a particular aquatic environment-system (freshwater, coastal or marine). Where a general definition is used such as “the culture or husbandry of aquatic fauna and flora”, the path is open for more specific regulations relating to a particular system, as the need arises. The participant from the R. O. Korea indicated that there are difficulties to control compliance with effluent quality standards, and suggested the use of environmental quality standards which fix the maximum allowable level of pollution in an environmental sector or target during normal periods.
iii. Economic and social aspects
139. The TCP Team Leader, Ulf N. Wijkstrom, introduced this subject. The economist's primary concern is the study of the behaviour of individuals as producers and consumers. The interaction between aquaculture and the environment for the economist can be seen as the effect that aquaculture activities have on the possibilities of others to produce and/or consume, and conversely, as the possibilities that aquaculturists have to produce as a result of the production or consumption activities of others.
140. The effect can take the form of a change in the prices for the production inputs (or goods and services) that the individual uses or it might take the form of a lower production (or a lower consumer satisfaction) from the same quantity of factors of production (or the same quantity of goods and services consumed). The price changes are handled by the economic system and is not of further concern in this context.
141. It is the imposed physical modifications in factors of production (or goods and services to be consumed) that is the central problem when considering the interaction between aquaculture and the environment. Such forced modifications are termed “externalities” by the economist.
142. They might be physical in character (modification of the quality of water, soil, air, the composition of flora and fauna, etc) or legal. The legal modification consist of changes in property rights (the economist understand property rights to be “the right to a future stream of benefits-monetary or non-monetary”).
143. The degree to which the individual can achieve compensation for externalities depends essentially on the expected “transaction costs”. Transaction costs include the costs the individual will need to incur in order to obtain compensation. They include costs for: obtaining information (who is causing the externality?), for negotiating an agreement with the “offender” and for monitoring that the agreement is respected. Obtaining information in matters of environmental impact is especially difficult in relation to physical changes. Who is causing the impact and exactly what is the relationship between the offending action and the decrease in my possibilities to produce (or consume). This relationship at times is referred to by economists as the “damage function”.
144. To arrive at a monetary estimate of the “damage function” is especially complicated in the case of negative impacts on “biodiversity”. Those who maintain that biodiversity is important do so for two reasons: either because it is essential for our possibilities to continue indefinitely to produce even from segments of the eco-system which we are not now knowingly using for such purposes (an “options value”) or because just the fact of knowing that a particular part of the eco-system is unchanged is pleasing (an “existence” value).
145. When the individuals (or groups of individuals) cannot agree on compensation for externalities, the government has the option to intervene. Naturally, the offended party calls on the government to intervene to stop the offender.
146. If the government agrees, its decisions will take the form of application of existing laws or introduction of new ones. To enforce the law concerned, the administration will have recourse to either “command and control” instruments, or to economic instruments. The latter will be designed so that the offending party will be either penalised for committing the offending (polluting) act, or given incentives to replace the offending activities by other non-polluting activities. Amongst the possible economic instruments to be applied in environmental matters are: user charges; product charges; tradable (emission) permits; and deposit-refund schemes.
The presentation on economic aspects appears as Annex III-8.
147. Professor Ruangrai Tokrisna, economics resource person, introduced the concepts used by economists to evaluate externalities, and alternative uses of natural resources. Three different valuation techniques were described: common evaluation techniques (productivity changes, loss of earnings, opportunity costs and preventive expenditures); surrogate market techniques (property values, wage differences, travel costs and shadow prices); and contingent valuation (survey based method). These tools will be useful when a government is to decide on issues such as the identification of different land use, as a preparation for the introduction of zoning.
The technical review of the economic aspects appears as Annex III-9.
B. Discussion of the study findings
148. The TCP team leader presented the findings of the TCP team study, with respect to the public management of inland and coastal aquaculture. The presentation for each aquaculture environment/ commodity group was followed by a separate discussion. The following record incorporates both the presentation and discussion that followed each presentation. In addition, the working groups produced further detailed environmental management options for: (i) inland aquaculture; and (ii) coastal aquaculture.
The working group reports detailing the environmental management options are in Annex III-10.
i. Inland aquaculture and the environment
Aquaculturists' impact on non-aquaculturists and on other aquaculturists
149. Type and magnitude of externality.
Physical:
Water quality.
Introduction of exotic species.
Loss of wetlands.
Possible impacts on biodiversity of species (other than the aquatic fauna and flora).
Magnitude:
Water quality - comparatively small (isolated cases a serious problem).
Exotic species - damage function not well known.
Other animals and plants - damage function not well known.
Legal:
Encroachment on land use (agricultural lands) and water use rights.
150. The workshop considered that views on the introduction of exotic species should be balanced. Three observations are in place. First, while the negative impacts (measured by the impacts on biodiversity) are considered here, it must be recorded that some introductions have been (economically) successful. A typical case in point is that of Sri Lanka where the introduction of Oreochromis mossambicus has led to a sustained fishery in a number of the largest reservoirs in Sri Lanka. At the same time, the tilapia has contributed, it is believed, to the eradication of a number of other fish species from the local fauna. Secondly, the fact that there is little information on negative impacts (i.e. on biodiversity) should not be interpreted to mean that there is none, or that none has taken place. It is obvious that all water bodies which could have been subject to such effects have not been studied. Thirdly, it is not easy to quantify (measure) the impacts on biodiversity as they occur and to predict them is even more difficult.
151. Considerations relating to loss of wetlands differ. In Myanmar to date, the use of wetlands for rice and rice-fish farming is not considered a loss. The vast amount of wetlands available means that possible negative impacts (on biodiversity) of the small percentage now under use, is marginal.
152. The legal issues concern the right to use water and the correct use of land. The conflict over water arises in water bodies subject to multiple use. In Nepal, when aquaculturists need to maintain water in irrigation reservoirs, farmers also need to apply it to their fields, or village communities may object to having fish cages in reservoirs or ponds from which drinking water is obtained. In the Indian sub-continent, agricultural land is often designated as such by law. Recently, expansion of pond culture on agricultural lands has often occurred in contravention of existing laws, as aquaculture is not considered a form of agriculture. Although this is mainly a problem with regard to the rapid expansion of shrimp culture, it also concerns culture of freshwater fish in ponds.
153. Non-aquaculturists' (and aquaculturists') success in eliminating externalities created by aquaculturists.
Water quality modifications: little success.
Introduction of exotic species: generally little success.
Loss of wetlands: little success.
Loss of land and water use rights: little success.
154. The water quality problem, except in isolated cases (e.g. very intensive culture of different species of air-breathing fish in Thailand having a negative impact on surrounding agricultural practices; intensive use of trash fish as fish feed in pens/cages in Cambodia) the problem has not been large enough to warrant a major effort.
155. Introduction of exotic species. The reason that the non-aquaculturists have not had much success in reducing the negative effects (on biodiversity) of introduced species is that they do not have the legal rights to interfere. Even if they had, it is an extremely difficult proposition to eradicate a species once introduced. Therefore, as a reminder to all concerned, the “horror stories” which have been reported from the region might be made widely known, as a deterrent against future illicit introductions.
156. In areas where it is crucial to maintain the remaining important wetlands habitats, the concerned individuals usually do not have the legal rights needed to obtain a modification in the planned use of wetlands. The legal problem with regard to land use is not experienced by the average farmer as an inconvenience in relation to freshwater aquaculture (the case is different with respect to shrimp farming, where salinisation of water and adjacent lands might occur). With regard to water rights, the issue has generally not been solved by private parties.
157. Management of the externality by the public administration: nature and success.
Externalities can be managed through modifications of user rights, such as:
Zoning for cage culture: successful.
Licensing for cage culture: at times successful.
Import permits for exotic species: generally not successful.
Rights to water and land: solutions have been found, but are slow at being introduced.
158. Introduction of exotic species. The appropriate procedures for evaluating the merits of introduction of exotic species are known. The problem remains one of achieving respect for the decisions taken in accordance with these procedures. This problem of course has an international connotation, as fish are able with ease to cross national borders in international water ways.
159. In Nepal, the legal issues relating to water rights are being tackled by involving local communities in the management of water bodies. This appears to be a successful approach. In India, several coastal states are introducing new legislation amending the regulations so that aquaculture can also be carried out on agriculture lands.
160. Study conclusions.
Adverse impacts on the environment through modification of water quality and use of wetlands is not a
widespread problem for inland aquaculture. It is a minor problem when compared to urban and
industrial pollution. However, the tendency is towards an increased intensification in inland
aquaculture, which will automatically increase the potential for an even more rapid growth in negative
impacts on the natural environment by inland aquaculture. It would seem prudent to develop a strategy
for public management of these potential impacts now.
161. The impact of introduction of exotic species has, in some instances, been recorded to affect biodiversity. The extent of this problem is not well known. Neither is it a problem that lends itself easily to quantification. It is not evident how public administration should manage the introduction of exotic species.
162. At present, most of the instruments used are of the “Command - Control” type (CCI). With few exceptions, it is felt that the legal instruments using (CCI) lack effectiveness. It might be useful to consider the addition of economic instruments (e.g. tradable permits).
The impacts of non-aquaculturists on aquaculturists
163. Type and magnitude of problem.
Physical:
Pollution of water and freshwater habitat destruction.
Legal:
Access to water (rights to use water) and land.
164. The problems are most severe in densely populated rural areas and in the proximity of urban environments (e.g. China and Hong Kong). It should be remembered that the pollution caused by inland aquaculturists as a whole is qualitatively different from the one they suffer. While the emissions of waste water from intensive inland aquaculture is essentially non-toxic (with the exception of the occasional use of chemicals), industrial waste, urban sewage and agricultural runoff is inherently more dangerous in character. In areas where rice-fish farming is an established practice (e.g. Indonesia) the effects of agricultural runoff on aquaculture can be quite devastating.
165. As populations grow, freshwater resources are coming under increasingly intensive use. It is quite natural that aquaculturists (who must recognise that they are net users of water through evaporation) are also seeing their entitlements to use of water being reduced pari passu with the rights of others. The restrictions so far do not seem to be a major concern although in some countries there is a discussion of the possibility of charging aquaculturists for the use of water. In others, there is concern to give aquaculturists more equal access to water.
166. Aquaculturists success in eliminating externality.
Generally: no success (non-point source; or too economically important). Inland aquaculturists have no,
or very limited, success in their efforts to limit pollution through direct negotiations with polluters. In
fact, they seldom try. The reason is that in case of agricultural runoff entering the culture unit with the
water collected in nearby streams -- and also with regard to urban sewage -- there are too many possible
offenders to talk to. It is a case of “non-point source” pollution. This means that it is difficult to
identify exactly who is responsible and to what extent amongst the large number of possible offenders.
Thus it is virtually impossible to establish the “damage function”.
167. In the case of industrial pollution it is sometimes possible to identify the polluter (e.g. an upstream sugar mill, paper plant), but impossible for the aquaculturist to afford the “transaction costs” involved in reaching a settlement.
168. Management of the externality by the public administration: nature and success.
Where success has been achieved, it is generally not imposed specifically on behalf of aquaculture. In
most instances, inland aquaculturists have represented too small an interest group to obtain any redress
through the public administration. They have been left to solve their problems exclusively by farm
management methods (e.g. switch to air-breathing species and culture in rainfed ponds using stagnant
water). Where redress has been obtained, it is generally because some larger interest group has forced
the solution. This is generally obtained through municipal sewerage and water treatment facilities
financed through user charges. Industrial plants are forced to adhere to emission standards.
169. Study conclusions.
Although public management of the environmental impacts created by inland aquaculture leaves room
for improvement, such efforts do not fall into the first priority for action. In most situations, it appears
that inland aquaculturists must form alliances with other groups affected by polluted waters, in order to
obtain the “weight” necessary to achieve public management of the externalities. In order to form such
alliances, it might be necessary that inland aquaculturists obtain a change in the general perception of
them as polluters, e.g. with their present reputation it is difficult to form alliances with environmental
interest groups.
ii. Coastal aquaculture and the environment
170. The meeting devoted a considerable amount of time to discussions on coastal shrimp culture, an issue of major regional interest. There was also discussion on coastal mollusc and seaweed culture. Less time in the plenary session was spent on coastal finfish culture, although detailed discussions were held on issues related to seed supply for marine finfish culture. The workshop was concerned over the possible impacts of the collection of wild seed for aquaculture on native stocks -- noting examples of heavy exploitation of eel and grouper juveniles in some locations. However, little quantitative information was available on the subject. The environmental management options and suggestions concerning wild stocks are given in the working group reports in Annex III-10. The following reports the presentation and discussions concerning shrimp, mollusc and seaweed culture.
Coastal aquaculture: crustacean culture
The impacts of aquaculturists on non-aquaculturists (and on aquaculturists)
171. This section considers the impacts of the activities of shrimp farmers on non-aquaculturists and on other aquaculturists (mostly shrimp farmers).
172. Type and magnitude of externality.
Physical:
Mangrove removal.
Collection of wild larvae.
Illicit international trade in mature breeders.
Transfer of pathogens.
Salinisation of soils (seepage) and fresh water (pumping of fresh water).
Land subsidence.
Water pollution.
Magnitude:
None of these externalities are well quantified, but appear to be less serious than commonly thought.
Legal:
Forced reduction in the right of access of traditional users to sites developed for shrimp farms.
Magnitude:
Probably better known (at least locally).
173. While some of the countries now prominent in shrimp culture experienced the removal of mangroves during the development of the industry, the trend in these countries, and elsewhere (e.g. India) is to locate shrimp ponds behind the mangrove zone. It also increasingly recognised that it is not only shrimp farms that have been devastating mangroves (and in some cases still do so), there are other equally devastating uses, e.g. cutting the mangrove for fire-wood or charcoal, urban expansion and salt pan development. While the extent of the problem is becoming known, its impact in terms of effect on biodiversity or coastal fisheries, is still not well known.
174. Collection of wild larvae is a problem only in some countries (mainly India and Bangladesh). The effects have been quantified in terms of simultaneous destruction of other juveniles, but not the effects on commercial fisheries. In countries with established shrimp culture industries this is not a problem as most of the post-larvae used are reared in hatcheries.
175. Illicit international trade in mature breeders is potentially most damaging, as it might lead to the accidental introduction of pathogens. The magnitude of this problem is not known, but may be potentially serious.
176. Seepage of salt water into the water table surrounding shrimp ponds is a problem in most of the countries where shrimp culture is carried out. In spite of the relative ease with which this problem can be studied, with the exception of some studies in Thailand, the magnitude of the problem is not well known. The problem arises from pumping of seawater inland and sometimes groundwater extraction. The problem related to groundwater may decrease in importance as farmers realise (e.g. Thailand, Philippines) that they do not need to dilute sea-water for culture of the most common species of shrimp (P. monodon). The same applies to salinisation of drinking waters; the gravity and extent of the problem is not well known.
177. In Thailand and Indonesia, but apparently not to any noticeable extent elsewhere, faulty site selection (potentially polluted waters), lack of zoning of farms and inexperienced management has caused farmers to abandon their shrimp ponds. The economics of putting them back in use are not favourable in comparison to building ponds elsewhere.
178. Although non-aquaculturists, particularly the tourist industry, have complained that shrimp farming pollutes coastal waters to their detriment, it would seem most likely that the reverse is probably the truth. There are those who maintain that effluent from shrimp farms contributes to an enhancement of the productivity in coastal waters. However, the evidence for these claims is purely anecdotal. The polluting effects of shrimp farm pond effluents depends on the nature of the emission point and the resulting pollution is very different in the open sea than it is in a backwater or an estuary.
179. The establishment of shrimp farms on public lands, or on land designated for agricultural use, has led to a reduction to the rights of access of other traditional users. This is reported as common in the Indian sub-continent, but also occurs elsewhere. The most severe of these impacts are those instances where it restricts access to fresh water wells.
180. Non-aquaculturists success in eliminating externality
Physical
It is apparently quite common that no redress is obtained through direct contacts. The exception to this rule, in some instances, seems to concern supplies of fresh water; if removed, or damaged, attempts are made to replace them.
Legal
Same situation as for physical.
181. The group of individuals who are most effected by the establishment of shrimp farms are coastal communities, and amongst them artisanal fishermen. However, for them the problem is parallel to that suffered by fresh water aquaculturists as a result of the actions of urban dwellers (who pollute their freshwaters). Although it is known who the offender is (the shrimp farmer), the damage function -- with regard to effects on fish stocks -- is not known. Thus, there is no rational basis for argument. In some cases (e.g. southern Thailand), there are reports that shrimp farms have led to an increased abundance of certain finfish and shellfish stocks.
182. For the paddy farmer, the transaction costs incurred in obtaining compensation for saline paddy fields are probably quite large. It is reported in some of the country reports that shrimp farmers are attempting to compensate rural communities for the loss of fresh water.
183. In relation to the loss of access (a form of property right) there seems to be some success here in compensating rural communities for the lack of access of drinking water.
184. Management of the externality by the public administration.
Physical
Mangroves: formally yes -- command and control mechanisms are in place in several countries. In reality, generally no effective control.
Larvae: no management (Bangladesh, India).
Salinisation of soils: no management.
Salinisation water: in some locations formally yes, often in reality, no.
On the whole, public management of the negative impacts on the environment, and therefore on other groups in society, has not been markedly more successful than the private attempts to do so.
185. This relates in particular to the preservation of mangrove areas. Most countries have legislation in place to regulate the use of them. However, the CCI type instruments, which relied on this legislation, have generally proven ineffective. The management of trade in shrimp larvae and post-larvae is proving politically difficult. As long as the negative impacts have not been clearly demonstrated, it is difficult to introduce regulations which will remove the livelihood of thousands of families, while not visibly providing substitute employment possibilities.
186. Study conclusions.
Public management of the externalities created by shrimp culture is important. The present reliance on
CCI type instruments does not seem to be successful. Involvement of stake-holders and use of
economic instruments may prove more effective.
187. The environmental impact of shrimp culture is indisputable. However, exaggerated statements about this impact are difficult to refute because of lack of quantitative information about the damage function. Given the general concern with deteriorating coastal environments (and quality of coastal waters) this lack of information seems to be particularly harmful to the interests of shrimp farmers. The preliminary studies which have been made show that shrimp farms are a minor contributor to pollution, and that it might be possible to have intensive culture systems which are less polluting than semi-intensive ones.
188. It should be recalled by the public managers in those countries where there are still large areas apparently suitable for shrimp culture activities, that there is unevenness in the suitability. This heterogeneity will cause entrepreneurs to congregate, if they are allowed, in the best areas. Thus, even if they were to occupy only a minuscule portion of the apparently available surface, it is important that their precise locations follow government regulations, in order to avoid the problems which seems to be automatic as soon as farms are allowed to congregate in a certain area.
The impact of non-aquaculturists on aquaculturists.
189. Type and magnitude of the externality.
Physical:
Pollution of fresh water and brackish water (e.g. oil-spills, agricultural run-offs, industrial waste, sewage from urban areas.)
Destruction of coastal habitats causing siltation and water quality changes.
Magnitude:
Intermittently, the externalities can be extremely costly (e.g. Thailand, China).
Legal:
None.
190. Shrimp farms located in coastal zones which harbour industry or agriculture may suffer the effects of polluted waters coming into shrimp ponds. In semi-enclosed areas (like the inner part of the Gulf of Thailand and the Bohai in China) the effects (often disease outbreaks on shrimp ponds) can be extremely damaging with complete crops lost. However, it is difficult to determine the relative contribution of self-pollution to such crop failures.
191. Aquaculturists success in eliminating the externality. As discussed in relation to inland aquaculture, it is extremely difficult for the individual shrimp farmer to obtain redress from a large number of farmers, urban dwellers or hotel owners for polluted waters. The farmers only choice seems to be to improve farm management (to reduce the incidence of disease) or to abandon or relocate the farm.
192. Management of the externality by the public administration: nature and success.
Physical:
Oil spills: compensation in some countries.
Agricultural runoff, industrial and urban pollution: little success in enforcing existing regulations.
193. While most countries have regulations in place to reduce industrial, agricultural and urban pollution of coastal waters, they are generally not strictly enforced. In some countries, the administration actively helps shrimp farms to obtain compensation from the guilty party (e.g. R.O. Korea and China)
194. Study conclusions.
The contribution of non-aquaculturists to the pollution problems experienced by shrimp culturists are
not well quantified. In spite of the economic importance of shrimp farming to many countries, there is
little effective assistance by the public administration to reduce the environmental externalities suffered
by shrimp farming. Also, shrimp farmers may have to team up with others who suffer the pollution of
fresh and coastal waters to obtain redress.
Coastal aquaculture: mollusc culture and seaweed culture
The impact of non-aquaculturists on aquaculturists
195. Type and magnitude of externality
Physical:
Pollution of coastal waters (e.g. urban sewage and industrial wastes, including oil spills) manifest in form of red tide, anoxia.
Magnitude:
An increasing problem for coastal areas with increasing population. Severe and irreversible?
Legal:
Rights to culture removed (land reclamation, e.g. Hong Kong and R. O. Korea). With increasing populations, industrialisation and intensification of aquaculture, the problem is increasing in magnitude and constitutes a potential threat to large areas of mollusc and seaweed farming in R. O. Korea, China and the Philippines.
196. Aquaculturists success in eliminating externality.
The farmers generally have no success in preventing the onslaught of polluted waters. They have few,
if any, management choices. The main one is to relocate their activities.
197. Management of the externality by the public administration: nature and success.
The public sector management of the externality is legal in nature. In some countries (China, R. O.
Korea) the mollusc culturist is assisted to obtain compensation from the economic unit causing
pollution. Also, there are instances when mollusc farmers are compensated, usually by the state, for
abandoning their activities in favour of land reclamation (R. O. Korea, Hong Kong).
198. In some countries aquaculture zonation has been introduced in coastal zones. Under these schemes, the rights of the mollusc farmer (this also holds for shrimp and finfish farmers) is protected by increasing the liabilities of those who are potential polluters of the coastal zone, as well as the mollusc culturist (dredging of bottom, occupation of small percentage of allocated zone). The degree of success is difficult to estimate. Where it has been tried (R. O. Korea) it has not been implemented with sufficient stringency to remove the incidence of red tides.
199. Depuration of cultured mollusc is not generally applied, partly for economic reasons. It is not feasible to arrange for depuration without incurring costs and as long as those costs are passed on to the producer (and from him to the consumer), depuration will be as difficult to introduce as other regulations of the “Command - Control” type.
200. Study conclusions.
Implementation of regulations intended to control the polluters of coastal waters are basically of the
“Command - Control” type. To improve the success in maintaining the coastal environment at low cost,
it might be useful to investigate the use of economic instruments. In the long run, mollusc culture and
seaweed culture will suffer greatly unless zoning is introduced to safeguard areas of relatively
unpolluted waters.
The impact of aquaculturists (mollusc and seaweed culture) on non-aquaculturists and aquaculturists.
201. Type and magnitude of externality.
Physical:
Sedimentation of excreta contributing to anoxia (mollusc).
Toxins leading to poisoning of consumer.
Magnitude:
Minor.
Legal:
Interference with rights of passage; spoiling (rights to unspoiled) scenery. This externality affects mainly other aquaculturists, principally other growers of mollusc or seaweed.
202. Non-aquaculturists (and aquaculturists) success in eliminating externality.
Physical:
Anoxia - can be handled by farm management practices (densities of installations, removal of deposits).
Toxins - not subject to farm management.
Legal:
No success.
203. In the countries primarily concerned (R. O. Korea, China and the Philippines) those installing seaweed or mollusc culture units normally have to obtain licenses to do so. These licenses serves as protection for the farmer against those who complain about the interference with right of passage and the like.
204. Management of the externality by the public administration: nature and success.
The R. O. Korea reports success in introducing public management measures of the concerned physical
effects. Mandatory farm management practices (including intermittent dredging of the sea-bottom
underneath long-line oyster culture) and specific regulations regarding the spacing of installations have
been used. Zoning is also being used to preserve coastal areas for aquaculture.
205. Study findings.
The impact of mollusc culture on non-aquaculturists (and on other aquaculturists) is manageable.
However, the accumulation of toxic substances is possibly more of a problem to be tackled by those
who are responsible for releasing the primary material that contribute to the development of these toxic
substances. To try to solve this problem at the aquaculturist level amounts to dealing with the
symptoms, not the root cause of the problem.
