shrimp aquaculture - impacts of shrimp aquaculture arise from: (i) the consumption of resources,...
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Swedish EIA CentreSwedish University of Agricultural sciences, SLU
State of the art
The Swedish EIA Centre
The Swedish EIA Centre is organised under the Swedish University of AgriculturalSciences. (EIA = Environmental Impact Assessment.) From January 2001 thehelpdesk staff consists of three persons with experience of EIA and work with or indeveloping countries.
The EIA Centre is commissioned to run a "helpdesk" for Sida (Swedish InternationalDevelopment Cooperation Agency) for questions on EIA/SEA. The helpdesk shall beready to help Sida and embassy staff in their daily work as it comes to questions onEIA. It could be anything from supplying addresses to persons or companies beingexperts in a certain area, review of EIA documents that have arrived to Sida, adviceon how to make terms of reference for EIA projects, and training of staff and Sidaconsultants in EIA.
Another task of the Helpdesk is to carry out special investigations and projects in thefield of development cooperation. Some of the reports produced are printed, and inaddition to this most of them are published on the home page of the EIA Centre,http://www-mkb.slu.se.
This report is produced as a special task given to Patrik Rnnbck, PR Konsult. Theopinion presented in the report is the author's own and does not necessary representthe opinion of the EIA Centre or Sida.
Rnnbck, P. 2001. Shrimp aquaculture - State of the art. Swedish EIA Centre,Report 1. Swedish University of Agricultural Sciences (SLU), Uppsala. (ISBN 91-576-6113-8)
In Asia, penaeid shrimps have for centuries been grown in traditional systems,with low productivity aimed for domestic markets. Export-oriented shrimpaquaculture is a fairly recent industry that took off in the mid 1970s. Withimproved technologies and the introduction of formulated feeds, the industryboomed in the following decade. In 1975, the shrimp aquaculture industrycontributed to 2.5% of total shrimp production, which gradually increased toaround 30% in the 1990s. Today shrimp farming makes up only 3-4% of globalaquaculture production by weight, but almost 15% by value. Around 80 percentof cultured shrimp come from Asia with Thailand, China, Indonesia and India asthe top producers. In the Western hemisphere, Ecuador is the major shrimp-producing country. The giant tiger shrimp Penaeus monodon accounts formore than half of the total shrimp aquaculture output. Other importantcommercial species are P. vannamei, P. indicus, P. merguiensis and P.chinensis.
The commercialisation of shrimp culture has been driven by lucrative profitsfrom export markets and fuelled by governmental support, private sectorinvestment, and external assistance. Despite the negative socio-economicsimpacts of modern shrimp aquaculture on the livelihoods of coastal communities,many bi-lateral and multi-lateral agencies have supported the development ofthis industry with large loans.
There are five different shrimp aquaculture practices, ranging fromtraditional to ultra-intensive techniques, but the most common techniques areextensive, semi-intensive, and intensive. These three categories are divided,according to their stocking densities, and the extent of management over grow-out parameters, i.e., level of inputs. The farmers that exercise extensive methodsrely on cheap land and labour, naturally occurring seed stock and feeds, and thelack of regulations which allows the conversion of coastal lands to shrimp ponds.Few input are required so producers can relatively easy enter the industry. Semi-intensive and intensive farming practices require the aquaculturist to implementmore control over the environment. Greater capital inputs, control of many grow-out parameters, and technical skills are needed. The potential annual shrimpproduction (ton per hectare) from these systems are: 0.6-1.5 for extensive; 2-6for semi-intensive; and 7-15 for intensive. The actual productivity is, however,much lower due to low quality intake water, variable weather conditions, andespecially disease problems. In 1999, the global average production was 650 kgshrimps per hectare pond, although most of the production was generated bysemi-intensive practices.
Shrimp fishery as well as culture practices are both fraught withenvironmental problems. For example, the discarded bycatch from shrimpfisheries alone comprise more than half of the total bycatch from all the worldsfisheries combined, and consequently shrimp trawling have major impacts onocean biodiversity and food web interactions. Environmental impacts of shrimpaquaculture arise from: (i) the consumption of resources, such as land, water,seed and feed; (ii) their transformation into products valued by society; and (iii)the subsequent release into the environment of wastes. The direct impactsinclude release of eutrophicating substances and toxic chemicals, the transfer ofdiseases and parasites to wild stock, and the introduction of exotic and geneticmaterial into the environment. The environmental impact can also be indirectthrough the loss of habitat and niche space, and changes in food webs. Thedeforestation of mangroves to accommodate shrimp ponds is perhaps the mostalarming single environmental damage. More than 50% of the worldsmangroves have been removed, and the establishment of shrimp ponds hasbeen a major cause behind this loss in many countries. As a paradox, theproductivity and sustainability of shrimp aquaculture is directly dependent on thecontinuos support of mangrove goods like seed and spawners as well asservices like water quality maintenance and erosion control.
The rapid expansion of shrimp aquaculture has also created severe socialand economic problems for coastal communities. Shrimp aquaculture oftenutilises common property resources such as mangroves and water. Thesecommon property resources contribute greatly to social equity, since netmonetary benefits are distributed to large groups of politically and economicallymarginal people. However, the development of aquaculture ponds transformsmangroves into a single-use private resource, and the opportunity forredistribution of benefits becomes limited. As a consequence, shrimp farminghas brought about social displacement and marginalisation of fishermen andagriculturists. The development of shrimp farms also has an impact on local foodinsecurity coupled to decreased agricultural production, depletion of drinkingwater, loss of mangrove forest goods, lowered fisheries catch, etc.
Shrimp aquaculture has exhibited a boom-and-bust pattern in manycountries, ever since 1988 when the industry first collapsed in Taiwan due todisease problems. Other top-producing countries, like, e.g., Thailand, China,Indonesia and Ecuador, have also experienced a rapid expansion of shrimpfarms that collapse within 5-10 years of operation. Diseases that once wererestricted to one region are now rapidly spreading over the world as a result ofthe expansion and globalisation of the shrimp industry. Disease problems have,however, not caused world shrimp production to decrease, simply because of a
sequential exploitation pattern, where new shrimp farms are developed at ahigher rate than farms are abandoned or left idle.
Deficient environmental management of shrimp farms is the most importantunderlying determinant to disease outbreaks. The risk of disease problemsincreases with intensity of farming and farm density in a given area. Wide-scaleabandonment of ponds is often due to the proliferation of initially successfulfarms that ultimately overwhelm the carrying capacity of the environment. Theecological footprint concept is one tool that can indicate the spatial developmentlimitations for shrimp aquaculture. For example, intensive shrimp farms require amangrove cover ecological footprint at least 22 times larger than the pondarea to filter the loading of nitrogen and phosphorous.
There are many recommendations on how to make shrimp aquacultureenvironmentally and socio-economically sustainable. The prevention of diseaseoutbreaks is a critical issue that will improve the financial viability of the shrimpindustry as well as reduce many of the environmental and socio-economicconcerns. Longer lifetime of individual shrimp ponds would reduce the relativeproportion of abandoned and idle ponds, and consequently the boom-and-bustpattern with sequential land exploitation is hampered. The worldwide transfer ofshrimps that are potential disease carriers would be reduced if hatcheries couldclose the shrimps life cycle and produce their own spawners. As a positive sideeffect the magnitude of the bycatch problem associated with wild-caughtpostlarvae, broodstock and spawners is reduced. Many approaches to combatdisease also focus on improved pond and water management aimed atameliorating the impact of shrimp pond effluents on the water quality of therecipient.
Making the proper choice of sites for the ponds is one of the easiest andbest ways for shrimp farmers to limit environmental damage and to improve thelifetime of their ponds. There is no defence for large-scale conversion ofmangroves to accommodate shrimp ponds. First, mangrove soils are not suitablefor aquaculture purposes. Secondly, the opportunity cost of convertingmangroves is very high in terms of (i) the substantial natural production of fishand shellfish supported by this system, and (ii) the impacts on the livelihood ofcoastal communities dependent on mangrove goods and services. Shrimpfarmers must also be trained to acknowledge the importance of viable mangroveecosystems for sustainable shrimp aquaculture production. Mangrove restorationprograms should be initiated in areas where shrimp aquacultur