Coastal Shrimp Aquaculture in Thailand: Key Issues for Research

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capacities of alternative organisms. Research examining a range of new species isneeded to find ones more suitable for the conditions in treatment ponds.Also, studies have to be made of the capacity of natural or artificial wetlands toassimilate farm wastes. All biological treatment experiments to date concentrate onthe ability of one or a few organisms to act in a steep-sided, flat-bottomed pond orcanal rather than the use of a complex and integrated ecosystem.Further, a number of bacterial and enzyme ‘bioremediation’ products are commerciallyavailable to treat aquaculture effluent. Research is under way into theeffectiveness of these products.Feeds and feedingThe dietary needs of shrimp are not completely known. Consequently, feeds areoften fortified with a range of vitamins and other supplements to guard against possibledeficiencies. This may be wasteful, and is being addressed by the feed producers,Charoen Pokphand (CP) and the Aquastar Company, and by the National Institute ofCoastal Aquaculture who are examining the effects of various feeds on shrimp healthand growth. These organisations are also trying to determine how to obtain optimalFCRs and are examining various species of phytoplankton for their suitability asshrimp feed. However, before such knowledge can be beneficial to the industry, thereneeds to be a better understanding of pond ecology so that environmental manipulationcan be used to stimulate appropriate phytoplankton blooms.DiseaseLike water quality, shrimp diseases are well researched, however the wide rangeof diseases which affect shrimp farming make them a priority for research. Currently,attention is directed toward disease identification, the development of new diagnostictests, disease treatments and improved knowledge of the immune system of shrimp.There is also a great deal of attention being given to the development of diseaseresistantstock.There still seems to be little study of the role of specific water quality parametersor sediment quality and disease. Also, little consideration has been given to the roleof a healthy bacterial population in the pond or a healthy gut and intestinal flora toeither disease development or the level of immunity in shrimp.An interesting finding of researchers at CP suggests another potential avenue fordisease research. Trials at CP demonstrated that extracts of an indigenous plantimproved the resistance of shrimp to viral disease when added to pond water (B.Withyachmnarnkul, pers. comm.). Research into the reason for the effectiveness ofthis plant in enhancing immunity may contribute much to the understanding of thedevelopment of viral disease and to understanding the functioning of the shrimpimmune system. Research to discover other naturally occurring immunoenhancersshould be consideredAntibiotic useThe use of antibiotics has the potential to induce the evolution of antibiotic resistancein disease-causing micro-organisms, to disrupt the natural pond microbialecology and to contaminate the flesh of prawns at the time of harvest. DOF has an$'
ongoing monitoring program to ensure that harvested prawns destined for export toparticular countries with strict antibiotic residue regulations meet these regulations.Farmers need to be made aware of the appropriate uses and dosages, and withdrawaltimes.SedimentShrimp farmers often remove sediment from ponds at the end of the productioncycle. The purported benefits of this process have not been clearly demonstrated.Research into this is needed.Pond sediment contains organic matter, residues of antibiotics and other chemicalsused in production, bacterial propagules and viruses, may be acid in reaction,and is saline. Shrimp farms in two districts in Thailand over a 40 km length of coastlinewere estimated to produce 2.72 million cubic metres of sediment annually. Thereis a need to develop improved methods for its disposal or treatment. Possible economicuses of sediment would also be extremely worthwhile. There has been talk ofprocessing the sediment for use as an agricultural fertiliser, but as it is generally highin salinity, processing would require salt removal. Appropriate methods to performthis need to be developed.Siting of farmsFarms in some areas are located on unsuitable sites, e.g. where there is an inadequatewater supply, on estuaries and canals with restricted tidal flushing, or wherethey interfere with ground and surface water flows. Farms are also constructed atdensities too great for the carrying capacity of the environment. This is a problemthat can only be solved by the introduction (and enforcement) of legislation governingpond siting, and the development of management practices which increase theefficiency of water resource use. Such approaches must be based on thorough environmentalassessment together with evaluation of economic and social factors.Shrimp farms which are no longer used may leave land unfit for agriculture. Incases where ponds were constructed in areas of natural habitat, the extreme physicaland biological alteration of the soil in the course of farm operation may inhibit successionof natural communities. Methods of remediating land left idle after shrimpfarming are required—either to allow it to be used for agriculture or to return it to thetype of habitat that previously existed. The growing experience on rehabilitation ofmangroves needs to be further expanded.EnvironmentResearch is needed to develop integrated coastal zone management policies basedon regional geographic, hydrological, ecological, economic and social considerations.Most importantly, research needs to be carried out to determine the appropriatetotal shrimp farming area for each region and how it should be balanced by other landuses for maximum socioeconomic benefit and to maintain ecological integrity.EducationWidespread education of farmers on good management practices is required.Several studies have shown that many farmers do not have access to information$(
Page 8 and 9: !The 1994 Workshop had a working hy
Page 11 and 12: !The Workshop at Hat Yai, SongkhlaA
Page 13 and 14: !ReferenceSmith, P.T., ed.. 1999. T
Page 15 and 16: !Shrimp Farming in ThailandOver the
Page 18 and 19: ! !Table 1. World production (# 1,0
Page 20 and 21: !Domestic and world demandJapan is
Page 22 and 23: !Intensification of farms has been
Page 24 and 25: !no significant difference between
Page 26 and 27: !Production Practices and Technique
Page 28 and 29: !use water which is almost fresh (F
Page 30 and 31: !mended quantities for application
Page 32 and 33: !the biological processes in sedime
Page 34 and 35: !factors (Fegan 1994). Environmenta
Page 36 and 37: !Acid sulphate soils occur in most
Page 38 and 39: during the rainy season, some deter
Page 40 and 41: Land subsidenceCoastal land subside
Page 42 and 43: first when an area becomes environm
Page 44 and 45: !Administration. Their work has inv
Page 46 and 47: agriculture, selects coastal land p
Page 48 and 49: Sustainability, Sustainable Develop
Page 50 and 51: cultural and environmental asset va
Page 52 and 53: $+Table 12. (cont’d) Impediments
Page 54 and 55: $#Table 12. (cont’d) Impediments
Page 56 and 57: $%Table 12. (cont’d) Impediments
Page 60 and 61: sources. This is one of the greates
Page 62 and 63: Table 13. (cont’d) Summary of the
Page 64 and 65: Boonyapiwat, S. 1989. Species of ph
Page 66 and 67: Katesombun, B. 1992. Aquaculture pr
Page 68 and 69: Sirisup, S. 1988 Socio-economic cha
Page 70 and 71: !In the preliminary analysis, the s
Page 72 and 73: !until all variables had been teste
Page 74 and 75: !quality problem over the past 3 ye
Page 76 and 77: !Figure 1. Characterisation of prov
Page 78 and 79: !Variables Contributing to Shrimp P
Page 80 and 81: !Figure 5. Relationship between ave
Page 82 and 83: !southern). The linear regression m
Page 84 and 85: !Appendix. Results of logistic regr
Page 86 and 87: !2) Trat ProvinceClassification tab
Page 88 and 89: !Chi-square df significanceModel Ch
Page 90 and 91: !8) Satun ProvinceClassification ta
Page 92 and 93: !Variables in the equationConstant
Page 94 and 95: !A total of 49 participants were in
Page 96 and 97: ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !Fi
Page 98 and 99: !All issues are listed in Appendice
Page 100 and 101: !!were short term and one issue was
Page 102 and 103: !reared broodstock (issue 71). They
Page 104 and 105: !!Two participants commented that i
Page 106 and 107: mation transfer and training. This
Page 108 and 109:
108Appendix 1. (cont’d) Descripti
Page 110 and 111:
Page 112 and 113:
112Appendix 2. Descriptive statisti
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Appendix 5. (cont’d) Descriptive
Page 124 and 125:
Appendix 7. Descriptive statistics
Page 126 and 127:
Appendix 7. (cont’d) Descriptive
Page 128 and 129:
Page 130 and 131:
!ParticipantsAustraliaDr Paul T. Sm
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