Seminar on Aquaculture Industry: Prospects and Issues. 22-23 August 1996, Bhubaneswar, Orissa, India. Organized by Confederation of Indian Industry
The Sustainability of Shrimp Farming
John Hambrey, Agricultural and Aquatic Systems program, Asian Institute of Technology, Thailand.
1. Is Current Shrimp Farming Practice Sustainable?
The idea of sustainability has been interpreted widely to cover a wealth of different perspectives. Although there is much theory on the subject, very few authors have offered realistic and simple practical guidelines or methodologies for the assessment of sustainability. Box 1 offers a suggested starting point. A general assessment of the sustainability of shrimp farming, based on this framework and the more detailed discussion in the paper, is presented in appendix 1.
Although it is not possible to go into all these these aspects here, some key elements will be considered.
It is often suggested that extensive or semi-intensive production is more sustainable than intensive production; indeed, it is commonly suggested that intensive production is unsustainable. This view derives from a narrow interpretation of sustainability, and confusion between correlation and causation.Sustainability depends not on the level of intensity, but rather on the quality of the site, the management, and the suitability of the technology to both site and management competence. Unfortunately, because of poor site selection and management, much shrimp farming in recent years has not been sustainable; and although some of the failures relating to intensive production have been spectacular, there have also been major problems with extensive and semi-intensive production. Different levels of intensity may be more or less sustainable in different ways; and different levels of intensity may be more or less sustainable in different economic or ecological contexts. Table 1 compares intensive, semi-intensive, and extensive shrimp farming according to a range of different sustainability criteria related to some of the relevant areas listed in box 1. The degree of sustainability assigned to each kind of shrimp farming will depend on the relative weight given to the different aspects, and the social, economic, resource, and ecological context in which development is taking place. It is impossible to generalize about sustainability of production, which will depend upon local circumstances (eg seed availability; water source; feed supply; management; disease etc)
In the following sections different aspects of sustainability (as outlined in box 1 and table 1) will be discussed in more detail, and will be related to intensity where relevant.
Box 1: Sustainability Assessment
In assessing the sustainability of any enterprise or technology, consideration should be given to at least the following:
∑ the sustainability (or continuity) of supply, and quality of inputs;
∑ the social, environmental and economic costs of providing the inputs (eg depletion of resources elesewhere);
∑ the long term continuity (or sustainability) of production;
∑ financial viability;
∑ social impact;
∑ environmental impact;
∑ the efficiency of conversion of resources into useful product.
In practice this amounts to a thorough economic (in the broadest sense) analysis, long term investment appraisal, and environmental impact assessment.
Table 1: Intensity and Some Aspects of Sustainability
aspects of sustainability
(IRR, payback period)
return on labour
nutrient conversion efficiency
risk of production failure
long term sustainability of production
1.1 Sustainability of supply and quality of inputs
In many countries seed is still caught in the wild. The supply of such seed cannot be guaranteed; its availability is generally seasonal; and it may carry disease. At high levels of exploitation, the collection of wild seed may have deleterious effects on wild capture fisheries (for shrimp and other species), and on the coastal ecosystem - either directly through removal of shrimp juveniles, or removal of other species in the by-catch. Hatchery produced seed on the other hand may also suffer from erratic supply related to disease or broodstock availability. The quality may be poor as a result of excessive use of chemicals, the practice of multiple spawnings, and poor feeding (eg related to a shortage or high cost of artemia cysts). In general however, hatchery production offers much greater potential for real long term sustainability and quality control.
While formula feeds are dependent on fishmeal there remains the question of the sustainability of exploitation of the source fishery, and the stability of supply. Imported feed degrades rapidly during storage in tropical countries and quality cannot be guaranteed. Formulation is still often more closely related to ingredient costs than nutritional and environmental requirements. In some cases, feed has been suspected as a source of disease. As noted above, the supply of Artemia cysts - mainly from the US and China - is erratic and quality variable.
The supply of chemicals is likely to remain relatively reliable and will probably increase. Quality is however frequently questionable. A huge range are now available to the shrimp farmer, especially in countries like Taiwan and Thailand, but neither their effectiveness nor their environmental impact are well documented. Heavy use of antibiotics may lead to disease resistance of pathogens of shrimp and possibly of humans. Heavy use of chlorine compounds for water or pond sterilization may lead to the formation of toxic chloramines and other complex organics.
The skills required for aquaculture production increase steadily with increasing levels of intensity. Although it may be relatively easy to achieve very high rates of output on a virgin site, sustained production at high levels of intensity requires high skills levels.
1.2 Sustainability of Output
Disease is by far the most serious threat to the sustainability of shrimp farm production. In Asia the viruses MBV, Yellowhead, and whitespot have caused devastation in many countries, and a variety of Vibrio bacteria cause intermittent problems. It is possible that Thailand is currently experiencing a crash similar to that which devastated the Taiwanese industry in the late 80ís and the Chinese industry in the late 90ís. In Latin America Taura syndrome continues to cause serious mortality in many areas. Much has been said about the relationship between intensity and disease, but extensive and semi-intensive producers have been affected at least as much as intensive producers in recent years.
Poor feed quality may reduce growth, depress health and survival, reduce water and pond soil quality, and increase pollution. It is also possible, though not proven, that it may transmit disease.
Poor water quality, caused by acid sulphate soil conditions, pollution (self, other farmers, other) or the presence of disease organisms may reduce growth, depress survival and introduce disease.
1.3 Financial Sustainability
Fish meal costs are likely to rise in the medium/long term as a result of steadily increasing demand, and steady or declining supply. Much will depend upon the rate of development of alternatives. Artemia used for hatchery production is likely to rise in cost as a result of steadily increased demand. At present there are very few major sources (US Great Salt Lake, China, and some production in Vietnam). Alternatives, including culture, are possible, but not competitive at the present time. Improved artificial substitutes are also possible but some natural food seems to be essential for good growth and survival.
Cost of Chemicals
The cost of chemicals is unlikely to rise substantially and new ones are constantly appearing on the market. Better site selection, design, husbandry, and water supply should reduce dependency on and cost of chemicals.
Labour costs are related to the stage of development of the country. Less developed countries have a clear comparative advantage in this regard, but as they develop further this advantage will be reduced, and advantage in terms of other resources or sites will become more important.
High quality water supply may be very costly in several regards. A site with good water supply may be expensive or have other features which are undesirable and lead to extra production costs. The development of infrastructure for the supply of water is costly. Water pre-treatment is also costly. Furthermore, as the industry (and other industries) develops, the demand for good sites and high quality water will increase, and the supply may decrease (in terms of quality and quantity), leading to a further escalation of price.
Product Value and markets
Product quality is increasingly important in all markets. Product quality may decline over time in poorly managed intensive systems as a result of disease, chemical residues, and smaller sized product.The average market price has been remarkably firm considering the steadily increased rates of production. However, there have been some unexpected oscillations (for example a significant price drop in the Japanese market due to low demand following the Emperorís death in the late Ď80s.
At the present time there is a real danger of declining demand in American and European markets due to the poor poor environmental and social development image of shrimp farming. Many Americans now think that all shrimp farming involves the bulldozing of pristine mangrove, driving out local people, making a lot of money, using massive amounts of chemicals, spreading disease, and then abandoning a degraded environment. It is even possible that environmental groups will force a ban on the import of farmed shrimp from Asia unless it can be shown to be environmentally sustainable.
Following major growth in the 80s, prospects for market growth in Japan for black tiger shrimp (P monodon) are limited. The US and European markets still have good growth potential, but only if the image of the product can be improved. The Asian market continues to grow well, and is less sensitive to environmental image.In terms of production effects on price, disease is likely to continue to cause problems in many areas, and act as a brake on excessive production and consequential reduced price. This is an interesting example of a sustainability conundrum: lack of sustainability among some producers may secure sustainability for others. Production from wild fisheries is likely to stay steady or decline.
1.5 Socioeconomic Sustainability
A variety of socio-economic impacts have been described in different parts of the world, including displacement of local people as a result of increased land value; decreased land quality (eg salinization; acidification; subsidence); and resource appropriation (government allocation through concessions of previously held common property resources, which had been used for a variety of subsistence uses by local people ); and interference with navigational rights and conflict with the fishing industry. There is little doubt that these impacts have taken place in some areas, but by no means in all countries or areas.
It has also been suggested that the shift from subsistence agriculture and use of natural resources to employment on large fish farms may represent a decline in quality of life. This is a political, not a scientific issue and it is the job of scientists and economists to provide information on these issues rather than make value judgements.
1.6 Environmental Sustainability
Like all human activity shrimp farming has a variety of direct and indirect effects on the environment. Direct impacts include habitat destruction. Mangrove is the most frequently quoted example, but a wide variety of other coastal ecosystems may be lost or affected, including estuarine and saltmarsh habitat, and other kinds of wetland.
Shrimp farming is also responsible for a variety of pollutants including organic matter (creating biological demand or BOD); nutrient enrichment (mainly nitrogen and phosphorus); and chemical discharges including antibiotics, pesticides/piscicides, and disinfectants.
A variety of indirect impacts can also be identified. The wild seed fishery may affect other species that depend upon this food source - including shrimp fishermen. It may also affect other species directly through the by-catch of species caught by default and discarded. Loss of habitat may also affect other fisheries such as small scale shrimp or mud crab fisheries, although extensive or semi-intensive ponds are probably a suitable habit for the latter species.
2. What can be Done to Improve Sustainability?
Sustainability can be improved as a result of individual initiatives, cooperative initiatives, and government initiatives. If shrimp farming is to grow successfully and sustainably it is probable that all three types will be required, but government must play a pro-active role in facilitating such initiatives.
2.1 Site Selection and Farm Design
Site selection is up to individual entrepreneurs, but can be guided or encouraged by government through incentives, education and information. There are many documents offering guidance in this regard and the subject cannot be covered adequately here, but some general principles may be offered.
The landward fringe of mangrove or non mangrove areas are generally better than pristine intertidal mangrove, both in terms of suitability for shrimp culture and in terms of lack of value for alternative activities or physical and ecological functions. However, it should be remembered that many coastal habitats other than mangrove have high value - indeed, many have higher value than much of the mangrove.
Many mangrove areas are of low suitability for aquaculture because of potential acid sulphate soils which become acidic upon exposure and drying, which normally takes place regularly in intensive and semi-intensive culture. In general clay or loam soils are most suitable (in terms of pH and water retention). Some fine sandy soils may also be appropriate.
The presence of other farms nearby is a strong negative factor because of the increased potential for disease spread or poor water quality. Well planned separation of water supply and disposal will ameliorate this problem, but disease may spread as wind borne aerosol and separation as far as possible is therefore desirable - if rarely possible. As a general principle there should be no, or limited, upstream or downstream production. Furthermore, the farmer must ensure that his/her own influent and effluent are clearly separated with effluent well downstream, or ideally entering a completely separate water system. The provision of appropriate infrastructure (see below) should facilitate such design.
Good access to supplies and markets is clearly desirable.
Both the cost and the environmental impact of feed may be reduced through lower nitrogen and phosphorus content. Lower protein content is possible if the quality is good and the content of essential amino acids such as methionine and lysine is adequate. Fish meal substitutes should be developed for these reasons, and also to reduce pressure on the capture fisheries which supply the product.
Extensive systems have the advantage of maximizing the use of natural food. There is some evidence however that highly intensive closed systems may offer the shrimp a wide variety of natural organisms, including plankton and bacteria, and that this may represent a further opportunity for reducing the protein content of feeds.
Better husbandry, better quality water, better quality feed, and better quality seed will all reduce the likelihood of disease and the need for and use of chemicals.
An increase in hatchery produced seed will reduce impact on wild stocks and allow a greater degree of quality control. Improved hatchery practice in terms of avoiding multiple spawnings, and better larval feed hatchery should be encouraged, perhaps through quality testing of seed. The introduction of disease certification is also technically possible and should be increased. Closing the breeding cycle rather than using wild spawners will allow for genetic improvement in terms of growth, food conversion aand disease resistance. Producing seed of alternative species - in particular P indicus and P merguensis - should also be encouraged. Different species show different levels of resistance to most of the common diseases, and production of a greater variety - either on different farms, or as part of alternating cycles on the same farm - will reduce risk.
2.4 Husbandry and Management
Good management and husbandry can have a major effect on all aspects of the sustainability of shrimp farming.
Pond and Water Management
In Thailand in recent years there has been a significant shift from high exchange (up to 20% of the pond water was exchanged each day) to more closed systems. There are three main types: semi-closed, where water exchange is minimized at the beginning of the production cycle and only changed as required toward the end of the production cycle; closed recycle, where production pond water is discharged to a settling pond/reservoir before being recycled into the production pond; and closed pond, where minimal water exchange takes place in the production pond, and water quality is maintained using intensive aeration and manipulation with a variety of chemicals and additives.
The management of pond soil and sediments in intensive systems is also crucial to sustainability in terms of both water quality and environmental impact. Harvesting of production using a seine net may stir up pond bottom deposits rich in organic matter and lead to the release of a pulse of highly concentrated efflluent to the environment. Harvesting with a bag net at the outlet while draining the pond will on the other hand minimize disturbance. Similarly the removal of pond sediments using high pressure hoses will create a pulse of pollution, while drying and removal will minimize environmental impact, and may lead to the production of usable fertilizer or soil conditioner.
2.5 Financial Viability
The main production costs in shrimp culture are feed, seed, and labour, with feed costs sometimes amounting to 50% of total operating costs. The greatest potential for the reduction of costs therefore lies in improved food conversion ratio. This can be achieved through good husbandry and possibly through improved feeding technology. Lin (1995) showed that smaller scale farmers in Thailand achived consistently lower FCR than larger farms, presumably through better feeding practice. In Taiwan some farms now use feeding trays to supply all food, and reduce feeding losses to the sediment. Staff training and extension should contribute to better husbandry and reduced feed costs.
Reduction in seed costs may depend on a competitive hatchery industry. Thailandís highly decentralized private hatchery network, with specialists for different stages of production ensures a highly competitive industry with relatively cheap seed. Reduction in labour costs is not necessarily desirable. Indeed, a local economic objective may be to minimize all costs other than labour. Cooperative purchase may also help in bringing down input costs
Increase Farm Gate Value
There are many different components to farm-gate value: the quality of the product, the image and promotion of the product in international markets, distribution and processing costs and mark-up, supply and demand trends in international markets.
Shrimp is an international product, and promotion should take place at an international level. Producers worldwide should therefore collaborate through their representative bodies (eg the Asian Shrimp Council) to promote shrimp, and initiate quality labelling initiatives and guarantees to consumers of environmentally sound production practices.
National infrastructure should reduce distribution and processing costs, but these are in any case generally scale dependent, and as the industry grows thay are likely to decline. Cooperative ventures on the part of producers may also facilitate marketing.
There is enormous potential for diversification into other species - either as an alternative to shrimp, and P monodon in particular, as part of an alternating cropping cycle including shrimp, or in conjunction with shrimp in polyculture systems. All of these approaches are likely to reduce the impact and severity of disease outbreaks and water quality problems. Candidates include edible and pearl oysters, seabass, grouper, P. indicus, merguensis and japonicus, and a variety of seaweeds.
2.7 Planning and Development
There is little prospect of sustainable shrimp farming without adequate and implementable planning for the industry. The disasters which have afflicted many areas in many countries can almost all be blamed on erratic and unplanned development with inadequate or poorly designed water supply, and in particular on mixing of influent and effluent water on individual farms and between farms. In Thailand the average farm shares its water supply with 30 others (ADB/NACA 1995). Planning must include:
- Identification of the best areas for shrimp and other aquaculture;
- Identification of value for other functions (eg nursery, protection, biodiversity, industrial development);
- Identification and discussion with stakeholders;
- Allocation/definition of development zones (aquaculture; other)
These zones must then be provided with adequate:
- Infrastructure in the form of water supply and disposal ensuring separation of farm influent and effluent, and possbly including some form of centralized water treatment;
- Extension, R&D;
- Marketing/processing/product quality labelling and certification initiatives;
- Hatchery and export product quality and disease certification schemes
However, such planning and support will have little effect unless farmers and entrepreneurs can be persuaded to operate within these zones and according to the rules. In this regard, incentives are generally more effective than constraints. A wide variety of measures may be used, including differential grants, credit, taxes or tax breaks, licenses, and concessions. These can be designed specifically to reinforce planning and zoning.In addition some regulations must be required, particularly those related to the control or regulation of stock movements and introductions.
2.8 Role of Government, Producers, Trainers and Researchers
Shrimp farming has the potential to be a highly profitable and sustainable industry, and the industry itself should therefore take on the burden of most of the above measures, at least in the longer term. However, the generally unsustained development of the industry in other countries demonstrates the need for a major leadership and facilitating role for government in the initial phase of development. This applies particularly to water supply and disposal infrastructure, which individual farmers are incapable of providing without the sophisticated organization and large amounts of investment capital which are only available in a mature industry. Government on the other hand is in a position to organize and fund infrastructure development, and eventually charge for its use if appropriate.
Farmers themselves should however play a major role in many of the other initiatives required, in particular the labelling, disease certification, marketing initiatives.
Academics, research and teaching institutions all have a potentially significant role to play in the development of sustainable shrimp farming; indeed the industry offers a large and expanding market for their products.
Intensive Shrimp Farming : Sustainability Analysis
Current Status of Shrimp Farming
continuity of input supply
- wild seed supply erratic and seasonal;
- hatchery supply may be erratic and subject to availability of wild broodstock;
- feed shortage or expense may arise related to variations in industrial fisheries supplying fish meal
- further develop hatchery seed supply;
- improve hatchery skills; close the breeding cycle;
- reduce fishmeal content of diet; increase contribution of natural feed
quality of inputs
- seed from wild may carry disease;
- hatchery seed may vary greatly in quality - multiple spawnings; poor feeding; excessive use of antibiotics;
- feed formulation - quality may be compromized in favour of low cost;
- feed quality may decline rapidly in tropical climate;
- skills and training frequently inadequate;
- quality and efficacy of many chemicals and other inputs questionable
|further develop hatchery production;introduce seed quality certification;|
- introduce feed quality standards;
- develop indigenous feedmill industry;
- provide improved vocational training;
- research efficacy of proprietory chemical products;
social, economic and environmental costs of inputs
- feed highly dependent on fishmeal from industrial fisheries, some of which are poorly managed and may not be sustainable; and whose intensive exploitation may reduce availability of other higher value marine species which feed on them.
- a wide variety of impacts may be related to the production of chemicals
- use of wild seed may reduce recruitment to capture fisheries; affect other species dependent upon them; and result in significant by-catch of discarded juveniles of other species
|reduce fishmeal content of feed; develop alternative protein /amino acid sources;|
- reduce dependence on chemicals through disease prevention: better husbandry, feed quality, site and water quality, water management, water supply and discharge design and infrastructure
- increase hatchery production of seed.
continuity of output
- disease is a major factor reducing the quantity and continuity of output;
- declining pond soil and water quality may result in a steady decline in growth and output and increased susceptibility to disease
|emphasise disease prevention: better husbandry, feed quality, site and water quality, water management, water supply and discharge design and infrastructurebetter pond soil and water management - training; water supply infrastructure|
- very high while production is maintained;
- often negative following poor management
|encourage moderate levels of intensity while skills are limited; intensify only slowly and steadily; initiate, facilitate and encourage training|
- return to labour, and employment potential/ha very high compared with agricultural alternatives in the coastal zone;
- investment/job high relative to more traditional agricultural and artisanal fishery activities;
- displacement as a result of increased land value; salinization; interference with navigation; destruction of habitat yielding susbsistence products for local people
- develop lower cost technologies
- consult all stakeholders prior to allocating previously commonly held land;
- zone aquaculture and agriculture to minimize chances of salinization
- previously unused brackishwater environments (eg mangrove, estuarine flats, saltmarsh) may be converted, resulting in destruction of relatively natural habitats;
- significant quantities of nitrogen and phosphorus released to environment (water, pond soil, air);
- significant quantities of organic matter (resulting in BOD) released to the environment;
- a wide variety of chemicals released to the environment, including disinfectants, pesticides, and antibiotics, the latter having the potential to cause increased resistance in bacteria.
|identify high quality natural habitat and enforce protection;set standards/guidelines/best management practice codes for effluent quality; encourage compliance through quality labelling initiatives related to both physical quality and production process;|
- ban excessive and inappropriate use of antibiotics, and use of those of particular value for the treatment of serious human disease;
- research possible impact of chlorination (disinfection) and production of chloramines and other complex chlorinated organics;
- poor conversion of protein (nitrogen) and phosphorus;
- moderate-high energy productivity;
- very high high land and labour productivity;
- high capital productivity
|improve feed quality and reduce N nd P content;good siting and infrastructure to reduce pumping requirement; improved aerator efficiency;|