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Annex II Country Reports (Cont.)

Annex II-8


Hak Gyoon Kim, National Fisheries Research and Development Agency, Kyongsangnamdo.

Oyster long lines in the coastal waters of the Republic of Korea.


In 1991, aquaculture production in the Republic of Korea amounted to 789,677 tonnes, with an economic value of 0.36% of GNP. Coastal aquaculture is more important than inland culture; out of a total of about 40 species cultured, more than 30 are marine species. From the production point of view seaweed culture is more important, but finfish culture is most important with respect to environmental impacts. Seaweed culture is mainly carried out in the south-western part of the South sea, but finfish and shellfish are mostly cultured in the south-eastern part of the South sea.

Under current regulations, all aquaculture activities should have a license which controls culture methods and stocking densities. Monitoring results show that most of the south-eastern coastal waters are eutrophic, or under the process of eutrophication, mainly caused by domestic and municipal wastewaters. Only in Hakrhim island near Chungmu city have water-borne pollutants originating from intensive finfish culture possibly influenced water quality. Harmful algal blooms, shellfish intoxication and summer anoxia are three important constraints to aquaculture, as they lead to a reduction in aquaculture production per unit area; sedimentation of organic substances; and the disruption of benthic and pelagic flora and fauna. The damage to fisheries has now become a socio-economic problem. To respond to these problems, the Environmental Protection Law (Law No. 3078, 31/12/1977) has been strengthened and specialised into several laws and regulations such as the Principal Environmental Policy Law (Law No. 4257, 1/8/1990) and the Aquatic Environmental Protection Law (Law No. 4260, 1/8/1990). Much governmental and non-governmental effort is needed in areas such as: monitoring, wastewater treatment, regulation enforcement and water quality management.

Map of the Republic of Korea.

Map of the Republic of Korea.


Korea geographically is a peninsula on the eastern coast of the Asiatic continent. The population is 43.5 million, with a high population density of 438.4 person/km2 at the end of 1990. Consequently, industrialisation and the growth of urban communities has brought about various changes in land use in the country. Korea has had programmes aimed at utilising the coastal and offshore resources of the country for a long time and projects, such as the reclamation of coastal land and designation of coastal areas for special purposes, have already been undertaken. The sound use of coastal areas is a significant challenge because the nation is poorly endowed with land resources and the coastal shelf area is three times that of the terrestrial area. There is thus considerable potential for resources and space utilisation in the coastal environment, and aquaculture development is particularly attractive as Koreans prefer marine products to beef.

After the foundation of the National Fisheries Administration in 1966, Korea devised a policy which stressed the growing importance of aquaculture. A sea-ranching programme to enhance coastal productivity was set up with high investment to develop aquaculture techniques. Therefore, coastal aquaculture and coastal industries have been well developed for at least two decades and about 800,000 tonnes of aquaculture production is obtained annually from coastal areas. Water-borne pollutants from terrestrial lands exceed the self-purification limit in some coastal areas, particularly where the water is shallow, tidal action is slow and pollutant load from the land is high. Water quality in the west and south coasts are susceptible to eutrophication leading to damage to the marine environment. However, the eastern coast has relatively good water quality due to greater dispersion and fast tidal movement. Recently, incidents of marine pollution by shipping and other marine activities have become important with respect to coastal pollution. Moreover, the reclamation of coastal lands and discharges of sewage during the last three decades have contaminated important and valuable marine living resources. Land reclamation projects, particularly forest area cultivation for agriculture, have caused some serious effects such as erosion, changes in water resources management and siltation in rivers, lakes and coastal areas. Recently, intensive culture has also caused eutrophication in some areas. The effects of this pollution and eutrophication have manifested themselves in three ways, namely: dinoflagellate blooms; seasonal anoxia; and shellfish intoxication, which appear in coastal waters each year. Meanwhile, as industrialisation and urbanisation are expected to continue, marine pollution will accelerate and be increasingly pushed off-shore, which will have an injurious effect on the aquaculture industry. Accordingly, the Korean government has established a National Integrated Action Plan to efficiently carry out marine environmental conservation policies and develop a plan to improve legal and systematic policies for propelling the plan positively and effectively. In addition to these domestic works, international and regional collaborations are inevitable to manage aquaculture development and assess environmental impacts.


3.1 Inland and coastal resources

Table 1. Inland and coastal resources of the Republic of Korea.

Lakes and reservoirs110,635 ha(5,563 water bodies)
Rivers and streams4,173 km(17 rivers and 84 streams)
Coastline12,800 km 

Along the 12,800 km of shoreline, there are 303,801 ha of coastal aquaculture areas, of which 180,017 ha (nearly 60% of the sites) are already exploited for mariculture. These are distributed mainly in the southern and western coasts of Korea.

3.2 Total aquaculture production, contribution of aquaculture to GNP

Due to high productivity and the seafarming programme, aquaculture products contributed 789,677 tonnes, or 24% of total fisheries production, in 1991. However, production had decreased compared with previous years (Table 2), partly due to eutrophication in shellfish farms and partly to a reduction in the export of algal products to Japan.

3.3 Species cultured, culture system and methods (Table 3)

Common carp, rainbow trout and eel are the important culture species in inland aquaculture. Marine fish culture systems have become widespread in Korea since 1964 and significant technical improvements, such as net cage culture and land based tank circulation culture systems, have been used to farm various other valuable finfish such as red seabream, flounder and yellowtail. Molluscs are farmed using two different culture methods; a long-line system for oysters and mussels and a bottom planting system for arkshells. Major cultured seaweeds include laver, sea mustard, kelp and fusiforme. The laver culture is practised by means of pole and floating net systems, while sea mustard and kelp are cultured by long-line systems. Large-scale farms for oriental prawn and kuruma prawn are located in the west coast and are now reaching a commercial level of harvest. In 1986, there was an area of 259.5 ha used for various kinds of finfish culture, coastal mollusc farming occupied an area of 39,516 ha and seaweed farms covered an area of 48,532 ha along the coastline of the Republic of Korea.

Table 2. Total aquaculture production and contribution in GNP.

Production (tonnes)975,568897,733859,842788,569789,677
Value (000s US $)440,295550,971550,223637,115736,364
Production as % of GNP0.32%0.35%0.33%0.32%0.36%
Fisheries export earnings (000s US $)468,844589,991526,666456,570479,249
People employed132,451130,250119,747102,53098,289

(Source: 1992 Statistical Yearbook of Aquaculture Forestry and Fisheries : Ministry of Agriculture, Forestry and Fisheries)

Table 3. Species cultured, culture systems and methods.

SpeciesCultures system/methodsProduction
Inland finfish 13,247 
Anguilla japonica (Japanese eel)Pond system2,386d + e
Carassius auratus (Goldfish)Pond and floating reservoir240d
Carassius carassiusPond and tank reservoir13d
Cyprinus carpio (Common carp)do1,201d
Misgurnus anguillicaudats (Loach)do211d + I
Channa argus (Snakehead)do446d
Oreochromis niloticusRecirculating water system d
Onchorynchus mykissFlow-through cold-water system d + I
Onchorynchus kisutch (Silver salmon)do d + I
Onchorynchus mykiss (Rainbow trout)do1,250d + I
Mugil cephalus (Mullet)Pond system d
TilapiaPond and recirculating system d
Inland crustacea 146 
Inland seaweeds 1 
Inland mollusca 2,756 
Cipangopaludina chinensis (freshwater snail)Pond and rice fields17d
Coastal, finfish 3,905 
Labeolabrax japonicus (Japanese seabass)Floating net cage377d + I
Seriola quinqueradiata (Yellowtail)do893d + e
Paralichthys olivaceus (Bastard halibut)Floating cage / land-based tank1,875d + I
Pagrus major (Red seabream)Floating net cage356d + I
Sebastes schlegeli (Jacopever)do d
Acanthopagurus schlegeli (Black seabream)do d + e
Takifugu rubripes (Tiger puffer)do d + I
Limanda herzenstein (Brown sole)do d
Oplegnathus fasciatus (Rock Bream)do5d + e
Mugil cephalusPond system8d
Pleurogrammus azonus (Atka mackerel) 16d
Coastal, crustacea 511 
Penaeus japonicus (kuruma prawn)Embankment culture/stocking31d + e
Penaeus orientalis (Prawn)do465d + e
Portunus trituberculata (Blue crab)do d + e
Metapenaeus joyneri (shiba shrimp)do15d
Coastal, molluscs 308,409 
Crassostrea gigas (Pacific oyster)Bottom and hanging (long-line)215,418d + e
Mytilus edulis (Mussel)do9,495d + e
Tegillarca granosa (Rock cockle)Bottom culture16,325d + e
Tapes japonicusdo d
Scapharca subcremata (Bloody clam)do d
Anadara broughtonii (Arkshell)do16,702d + e
Ruditapes philippinarum (Little clam)do45,537d
Pecten yessoensis (Scallop)Suspended and hanging tray culture.1d + e
Pectin albicans (Scallop)do d
Chlamys farreri (Scallop)do d
Haliotis discus (Abalone)Sea ranching, seeding and hanging tray culture.7d + I
Arca sp.Bottom culture d
Cyclina sinensis (Venus clam)do252d
Batilus cornutus (Top shell)do24d
Mactra veneriformis (Surf clam)do3,546d
Meretrix lusoria (Hard clam)do246d
Coastal, miscellaneous. 16,968 
Halocynthia roretzi (Sea squirt)Hanging culture (long-line)6,994d
Styela clava 9,972d
Coastal seaweeds 445,626 
Porphyra tenera (Laver)Fixed/floating (net structure)143,626d
Undaria pinnatifida (Sea mustard)Floating (rope structure)266,966d
Laminaria japonica (Kelp)Hanging long-line8,938d
Hizikia fusiformis (Fusiforme)Bottom and intertidal culture11,408d
Enteromorpha linza (Green laver)do14,367d
Monostroma nitidumdo d

Key: d = domestic;

3.4 Supply of inputs

Most coastal finfish culture relies on wild caught fry for stocking, but in the case of red seabream, bastard halibut and tiger puffer, a shortage of supply has led to the development of artificial production techniques. Culture of these fish requires the use of high quality feed, which is a major economic constraint to the industry. With the exception of abalone farming, which uses artificially produced seed, the majority of marine molluscs are cultured from wild seed. The sea squirt is cultured from artificially produced seed. Seaweeds, which constitute the majority of aquaculture production in the Republic of Korea, are artificially propagated and require very little additional inputs. In 1990, 130 million juveniles were released into the coastal area by NFRDA alone (Table 4). As for commercially cultured species, such as bastard halibut and red seabream, private hatchery enterprises produced most of the seed.

Table 4. The supply of artificial coastal hatchery inputs by NFRDA (Unit : x103 juveniles).

Scientific name1987198819891990
Total supply19,23625,93851,743130,590
Paralichthys olivaceus348265294168
Pagrus major304403457669
Acanthopagurus schlegeli---100
Sebastes schlegeli-8092160
Limanda herzenstein-10--
Haliotis discus175422109302051
Batillus cornutus---30
Pinctata fucata martensii200--65
Sulculus diversicolor aquatilis---20
Penaeus japonicus4800450050006200
Penaeus orientalis1070163033206850
Portunus trituberculata-500600750
Anthocidaris crassispina-50-150
Porphyra tenera Porphyra tenera---1000
Halocynthia roretzi107601236011500-
Paralichthys olivaceus (egg)-393028550109380
Pagrus major (egg)--10003000

(Source: Annual report of National Fisheries Research & Development Agency, 1987, 1988, 1989, 1990)

3.5 Legal framework

3.5.1 Access to aquaculture operations

Definition of aquaculture
According to fisheries law, aquaculture is the activity of artificial culture and harvest of aquatic animals and plants, including the utilisation of facilities such as fishing vessels and fishing gear for the culture and the installation of structures.

Aquaculture laws and regulations

LegislationFunction of legislation
1.Fisheries law.Defines aquaculture and sets licensing system. Management of fisheries resources.
2.Law for exploitation of inland fisheries.Sets licensing system for inland culture.
3.Regulation for license and management of culture beds.Sets management duty, culture methods culture species, siting and stocking density.
4.Aquatic environment protection law.Controls marine pollutants and sets monitoring requirements Sets water quality standard and special management of polluted coastal zone. Pollution mitigating measures to be taken in cage culture and the others larger than 1,000m2.
5.Principal environment policy law.Principal law of environment policy. Sets EIA requirements and standards.
6.Regulation for transplantation of marine living organisms.Regulates an introduction and management of exotic species into domestic coast.
7.Marine pollution control law.Controls effluents of oil and liquid wastes into coastal waters.
8.Law for management of hazardous chemical substances.Regulates use of toxic chemical materials. Evaluation of toxicity.
9.Law for management of public sea.Regulates the use of public sea.
10.Agricultural and fisheries relief law.Compensate damage caused by red tides and naturally occurred abnormal oceanographic phenomena.

Consent/authorisation mechanism
All aquaculture farms require licensing by municipal authorities.

Special consent system
There are codes of practice for the utilisation of lakes, rivers and coastal areas for aquaculture, which cover specific criteria governing site selection procedures and stocking rates for finfish, mollusc and seaweed farms. All cage culture and aquaculture of more than 1,000m2 in surface area should register to the Ministry of Environment, according to the Aquatic Environment Protection law. Major provisions aimed at mitigating the pollution load from cage fish farms consist of the following:

  1. Supply drifting and low phosphorus feed only and the sinking rate should not exceed 10% in two hours elapsed;

  2. Feed fences with a height of 10 cm above the sea surface should be erected to control the dispersal of feed outside of the cages;

  3. Delimit a difference of dissolved oxygen between inside and outside of cage within 20%;

  4. Facilities on the cages to retain human faecal materials;

  5. Regulation of the use of antibiotics and drugs for fish disease;

  6. Immediate removal of dead fish.

3.6.2 Environmental management of aquaculture

Water quality and water pollution control
There are standards that define acceptable water quality standards for aquaculture purposes. The quality of inland, coastal and fish farm water is monitored by the NFRDA. Large scale eel farms and cage farms are required to supply drifting feed and treat wastewater and sludge effluent to an acceptable standard. There are also regulations governing antibiotics and drug residues. Under “The Regulations Governing Sanitary Control of Shellfish and their Growing Areas” (Ministry of Agriculture, Forest and Fisheries, ordinance No. 699), the NFRDA undertakes surveys of shellfish culture areas. This includes routine sampling for sanitary indicator bacteria, shellfish poisoning, pesticides and heavy metals. The coliform median most probable number (MPN) of the water should be less than 70/100cm3 and not more than 10% of the samples should have a MPN of greater than 230/100cm3 during the most unfavourable hydrographic and pollutant conditions.

Environmental impact assessment
The Environmental Impact Assessment (EIA) law (Law No. 4567. Jun. 11. 1993) provides for EIA requirements prior to the construction of city and industrial complexes, port development, land reclamation and water resource development. However, the setting up of fish farms is not yet subject to EIA but it is likely to be so in the near future.

Control of the movement of fish
There is a provision regulating the transport of aquatic animals and plants in the regulation for transplantation of marine living organisms. This includes the introduction of new species, the quarantining of imported fish and the interdiction of the introduction of infectious diseases and recessive exotic species into Korean waters.

Control of toxic or hazardous substances and pharmaceutical preparations
Manufacture and usage of animal medicines is permitted and regulated by the Minister of Agriculture, Forestry and Fisheries. Codes of practice for the use of chemotherapeutants in aquaculture have been proposed by the Minister of Agriculture, Forestry and Fisheries by the law for management of hazardous chemical substances.

Control of pesticides
There are codes of practice for the use of pesticides and antibiotics on aquafarms for the treatment of disease. These codes, formulated by NFRDA, are guidelines for the application, permissible amount and interdiction period for harvest after use. In the case of oxytetracycline-HCL, the guidelines are shown in Table 5.

Table 5. Guidelines for the use of oxytetracycline in disease treatment.

Infected fishTreatment methodDisease namePermissible amountInterdiction period
Sea breamin feedVibrio50mg/kg/day30 days
Bastard halibutin feedVibrio50mg/kg/day40 days
Flat fishin feedVibrio50mg/kg/day40 days
Sea bassin feedVibrio50mg/kg/day20 days
Yellowtailin feedVibrio50mg/kg/day20 days
Prawnin feedVibrio50mg/kg/day25 days
Eelin feedVibrio50mg/kg/day30 days

Protected areas
The coastal areas of Ulsan, Pusan, Chinhae and Kwangyang Bay are designated as specifically controlled areas, protected against marine pollution.

Protection of indigenous species
There are regulations governing the introduction of new species.

Fish health
Dead fish in aquafarms should be removed immediately (Aquatic Environment Protection Regulation, article 14). When diseased fish are found in fish farms, farmers are required to notify local fisheries stations so that the authorities can survey the problem and take necessary precautions to prevent infection of other farms.

Product quality control
Standards exist for maximum permissible residue levels of mercury (0.7 ppm) in marine products. These standards were proposed by the Ministry of Health and Social Affairs and are monitored and enforced by the Ministry of Environmental Quality. Control of shellfish for export is administered according to the regulations governing sanitary control of shellfish and their growing areas. Bacteriological criteria for shellfish, prescribed in the regulations, stipulate that faecal coliform density and standard plate count (at 35°C) for fresh and frozen shellfish meat shall be less than 230 MPN/100gms and 100,000/gm, respectively.

3.6.3 Institutional framework governing aquaculture

1. Governmental organisations 
Ministry of Agriculture, Forest and Fisheries, 
National Fisheries Administration,Aquaculture development research.
National Fisheries Research & Development Agency.Monitoring of water pollution & red tides.
Utilisation and processing of marine products.
Ministry of Environment 
National Environmental Protection Institute.Environmental research and monitoring of coastal areas.
Ministry of Science and Technology 
Atomic Energy Bureau. 
Korea Atomic Energy Research Institute.Radionucleide materials.
Co-ordinator Biology and Ocean Research.National funding for special project for aquaculture.
Ministry of Home Affairs 
National Maritime Police.Controls oil pollution.
Municipal Fisheries Administration.Planning and licensing aquaculture.
Ministry of Education 
Department of Ocean Science.Teaches the importance of environment.
2. Non-governmental organisation 
National Fisheries University of Pusan.Training on environmental research and monitoring.
Korea Ocean Research & Development Institute.Research in oceanography and marine resources.

3.7 Government policy

The National Fisheries Administration is planning national aquaculture development and regulates the total quantity, licensing and economics. The Ministry of Environment is responsible for the national environment policy. The Korean government's national plan for inland and coastal aquaculture puts great importance on the promotion of environmentally sustainable aquaculture industries. Priority areas are:

  1. Biotechnological research on selective breeding and hybridisation of finfish and shellfish to maximise growth and production;

  2. Technological improvement of recirculating tank for intensive culture;

  3. Valorisation of nutritious and artificial fish feeds;

  4. Development of culture techniques for the culture of unexploitable species such as crustacea and invertebrates;

  5. Pathological and immunological study of fish disease;

  6. The development of aquaculture facilities based on the environmental carrying capacity;

  7. The production of more digestible feeds to mitigate the pollution load and reduce the supply of organic materials;

  8. Developing techniques for the restoration of polluted sediments in coastal shellfish and finfish growing areas;

  9. The development of wave resistant culture systems for off-shore culture;

  10. Polyculture research to make more efficient spatial use of the total aquatic environment.


Over the last two decades, the Republic of Korea has promoted sea farming projects to enhance coastal productivity and increase aquaculture production. The priorities of the Korean government were to develop new techniques in productive, stable and durable offshore culture systems. The rapid development of intensive culture techniques using cage, raft and long-line culture systems has increased the harvest from coastal waters. In 1991, coastal aquaculture production was 789,677 tonnes, representing one quarter of the total fisheries production.

However, eutrophication of some coastal areas as a result of terrestrial runoff and water-borne pollution (in some cases from intensive fish farms themselves) has resulted in annual red tide events, which are harmful to fisheries and human health. Recently, these incidents have increased in frequency, severity and duration and pose a significant constraint to the development of aquaculture in the Republic of Korea. Another important problem is shellfish contamination. Illnesses related to human health include PSP, DSP and ASP in Korea. PSP is the most serious and has been reported along the southern coast from March to June and its toxicity appears to be increasing. Oxygen deficient and/or anoxic waters also appeared in late July after the first dinoflagellate blooms. Therefore the major recent environmental issues affecting aquaculture are the occurrence of fish-kill red tides, shellfish intoxication and seasonal appearance of anoxic water. Other issues such as oil spills and the release of effluents containing toxic substances are also of concern to the industry. With respect to the beneficial effects of environmental changes due to man-made eutrophication, abundant planktonic biomass leads to high productivity of bottom commercial shellfish culture farms.

4.1 Impacts of external environment on aquaculture production

4.1.1 Inland aquaculture

Physical factors
Mining, pollution with solid matter, flooding, erosion and problems of water availability have had some limited affects on freshwater aquaculture. In addition, some soils are of an acidic nature. These are minor constraints to aquaculture development which are expected to continue in the future.

Toxic industrial wastes
There are no reports of industrial pollution affecting inland aquaculture.

Human and agricultural wastes
Demographic and livestock wastes have caused a limited degree of nutrient enrichment and microbial contamination. Eutrophication has resulted in blooms of phytoplankton of the class Cyanophyceae and Chrysophyceae in some lakes. This can lead to problems of low dissolved oxygen. Pesticide residues (including TBT) have also been found in inland waters, but their effects are not severe.

Petrochemical discharges
Oil spills have not affected inland aquaculture in the Republic of Korea.

Radioactive contamination
There have been no reports of radioactivity affecting aquaculture.

4.1.2 Coastal aquaculture

The realisation of development plans along the coastal zone in Korea has resulted in the degradation of coastal environmental quality. Over the last two decades, considerable amounts of domestic and industrial wastes were generated and discharged into these areas. Southern and western coastal waters in Korea are relatively shallow and therefore have a low assimilative capacity, which can readily lead to pollution of mariculture farms in the coastal zone.

Physical factors
Large scale reclamation of coastal land to provide new sites for agricultural and industrial purposes has caused problems for local aquaculture operations: 128,000 ha has already been reclaimed since 1988 and another 360,000 ha is scheduled for reclamation in the near future. Due to topographical characteristics, most of the reclamation has been conducted along the western coast bordering the Yellow Sea. These activities have influenced coastal ecosystems in several ways. Nursery grounds of marine living organisms have been destroyed, and the high turbidity caused by disposal of sediment can smother marine flora and fauna. Reclamation has also modified the direction and velocities of tidal currents. Moreover, when industrial complexes are built, it is likely that the chemical wastes generated will cause further problems for local fish farms.

Oxygen depletion in sheltered bays can cause significant problems for aquaculture and occurs as a result of thermal stratification, when water exchange between the surface and bottom waters is restricted. Organic materials which have accumulated in the bottom waters and sediments are broken down by bacterial decomposition and consume oxygen, which results in oxygen depletion in the bottom layer of water. This phenomenon has been observed in Chinhae Bay from July to October since 1989. When red tide organisms die, the mass of decaying cells are decomposed by bacteria resulting in oxygen depletion and causing fish mortalities. Storms and typhoons have damaged fish farms in the past. Additional problems of flooding, water availability, siltation and erosion have had limited effects on coastal aquaculture, as have mining operations and pollution with garbage and other wastes. Fluctuations in salinity and temperature and acid soils are minor constraints to further development.

Toxic industrial wastes
There have been no specific reports of toxic industrial wastes affecting aquaculture and results from an extensive pollution survey of sea water, aquatic organisms and bottom sediments suggest that Korean coastal waters are still relatively free from heavy metal contamination. However, efforts to recommend a total effluent control system are being made to minimise dangers to farms from these pollutants.

Human and agricultural wastes
Since the coastal ocean area is the ultimate receptacle of municipal waste and agricultural run-off, cultured animals and plants in estuaries, backwaters and coastal waters have become exposed to toxic pollutants. Domestic sewage in Chinhae Bay caused nutrient enrichment, eutrophication, dinoflagellate blooms and low dissolved oxygen affecting aquaculture.

Petrochemical discharges (see Figure 1)
Korea imports all of its oil, approximately 60 million kilo-litres every year. Oilspills by tankers often occur near Pusan, Gywangyang and Inchon port, and it has happened more frequently in the 1980s compared with previous years. The following two oil spills were major accidents which occurred between 1987 and 1991 in Korean coastal waters, causing damage to local aquaculture operations:

The first, in February 1988, damaged nearly 2,000 ha of marine aquaculture in Youngil Bay.

DateLocationVesselDischarge (kl)
24 Feb. 1988Youngil“Kyungsin-ho”(tanker)2,500(bunker-c oil)
15 Jul. 1990Inchon“Kores hope”(tanker)1,500(bunker-c oil)

Figure 1

Figure 1: Sites of fisheries damage caused by oil spills, dinoflagellate blooms and PSP in Korean waters.

Radioactive contamination
There have been no reports of radioactivity affecting aquaculture.

Phytoplankton blooms
Until the 1980s, only a few areas were affected by red tides and even then only sporadically. However, most of the coastal area is now threatened by harmful or toxic algal blooms as detailed in Table 6. During the period from 1981 to 1991 these mainly occurred in Chinhae Bay and its vicinity which receives large amounts of land-based terrestrial pollutants. Recently, blooms are beginning to occur in fish culture areas where the major pollutants are not terrestrial but water-borne. In August 1981, a bloom of Gymnodinium mikimotoi in Chinhae Bay (Figure 1) resulted in losses of oysters, mussels and arkshells amounting to US $ 2.6 million. In September 1989, US $ 70,000 worth of cultured yellowtail were destroyed due to a toxic bloom of Cochlodinium polykrikoides in the Hakrhim Islands. These events are increasing in frequency and severity and in August of this year (1992) a mass mortality of finfish occurred in Chungmu coastal zone, the largest area of intensive finfish culture in Korea. This massive fish-kill, caused by Gyrodinium sp., resulted in an estimated loss of US $ 8.6 million and replaced the 1981 event as the most damaging red tide to occur in Korean waters. Phytoplankton blooms generally occur along the south coast from spring to autumn, with the peak period from June to September. The duration of blooms is generally less than one week but since 1984, has continued sometimes more than two weeks in enclosed or semi-enclosed bays along the southern coast.

Table 6. Coastal areas of Korea affected by red tides since 1981.

Coastal AreaAlgal species
Inchon CoastNoctiluca
Chonsu BayNoctiluca
Mokpo CoastMesodinium
Cheju CoastGymnodinium
Gamak BayProrocentrium
Kwangyang BaySkeletonema
Chinju BayProrocentrium; Heterosigma.
Tongyoung CoastCochlodinium sp.
Chinhae BayHeterosigma; Prorocentrium; Gymnodinium; Alexandrium
Onsan BayProrocentrium; Heterosigma
Youngil BayProrocentrium
Ulgin CoastNoctiluca

Diatoms are usually dominant in spring and autumn and dinoflagellates are dominant in the summer. The major groups of phytoplankton causing the blooms consist of Dinophyceae, Rhaphidophyceae, Euglenophyceae and one ciliated species as listed in Table 7. Among the causative organism, diatoms such as Skeletonema costatum, Chaetoceros curvisetus and Nitzschia pungens were the most common species until the first half of the 1970s. Since then, flagellates such as Prorocentrum micans, P. minimum, Heterosigma akashiwo, Gymnodinium mikimotoi, G. saguineum, Alexandrium affine and Cochlodinium polykrikoides were found to be the main causative organisms. The trend for recently occurring red tides to consist of a large proportion of dinoflagellates, including toxic organisms, rather than diatoms is illustrated in Table 6. To date, 5 ichthyotoxic and 6 shellfish poisoning species have been identified in the marine environment (Table 8). It is reported that at a density of 1,000 cells/ml Gyrodinium sp. kills 8cm-long juvenile bastard halibut (Paralichthys olivaceus) within one hour. Toxic species such as this are extremely detrimental to the development of the finfish culture industry.

Besides the direct ichthyotoxic effect of some species, fish-kills are also caused by suffocation due to oxygen depletion, gill irritation and mucus secretions (Figure 2). In late July after the first dinoflagellate blooms, water masses become oxygen deficient or even totally anoxic. Bottom anoxia has killed benthic fauna and sometimes pelagic fish, when the deoxygenated water moves upward following destruction of the stratified layer by wind driven currents. Phytoplankton blooms can also cause unmeasurable but significant losses due to the decrease of culture productivity per unit area. For these reasons, red tides are considered a significant and growing threat to aquaculture development. High costs are incurred due to the need for preventative measures, US $ 143,000 is spent annually on a red tide monitoring programme. Since 1972, the NFRDA has investigated phytoplankton density and environmental parameters indicating eutrophic levels from February to November using research vessels in Korean coastal waters. This has provided an information base which is essential to coastal environmental protection policy and minimises fisheries damage due to red tides. When red tides occur, weekly observations are carried out. If the bloom develops to a large enough scale to cause damage to fisheries, the NFRDA alerts fishermen to take appropriate measures such as the movement of cages outside of the affected area, diminution of feed supply and adjustment of cage depth. Further co-operative research on ecophysiological aspects and control of dinoflagellates is necessary to understand the factors initiating and supporting the blooms.

Table 7. List of microalgae responsible for coastal blooms.

DivisionClassOrderRed tide organisms
(Genus, species)
CyanophytaCyanophyceaeChroococcalesAnabaena flos-aquae
CryptophytaCryptophyceaeCryptomonadalesChroomonas salina
DinophyaDinophceaeProrocentralesProcentrum dentatum
Procentrum micans
Procentrum minimum
Procentrum triestinum
GymnodinialesCochlodinium polykrikoides
Gyrodinium fissum
Gymnodinium mikimotoi (G. nagasakiense)
Pheopolykrikos hartmannii
NoctilucalesNoctiluca scintillans
PeridinialesAlexandrium affine
Alexandrium frateculus
Ceratium fusus
Heterocapsa triquetra
Scrippsiella trochoidea
ChrysophytaBacillariophyceaeCentralesChaetoceros curvisetus
Leptocylindrus danicus
Rhizosolenia alata
Skeletonema costatum
Thalassiosira allenii
Thalassiosira nordenskioeldii
PennalesCylindrotheca closterium
Nitzschia pungens
Nitzschia seriata
Navicula sp
RhaphidophyceaeRhaphidomonadalesChattonella sp.
Fibrocapsa japonica
Heterosigma akashiwo
EuglenophytaChrysophyceaeDictyochalesDictyocha fibula
ProtozoaEuglenophyceaeEutreptialesEutreptiella gymnastica
CiliophoraKinetofragminophoreaProstomatidaMesodinium rubrum

Table 8. Major harmful algal species found in Korean waters.

ToxicityGeographic AreaSpecies nameRemark
IchthotoxicSouthern CoastAmphidium caterae 
Chattonella antiqua 
Cochlodinium polykrikoidesFishkill, 1989
Gymnodinium mikimotoiFishkill, 1981
Cochlodinium sp.Fishkill, 1992
Gyrodimium sp. 
PSPSouthern CoastAlexandrium tamarense1986, two deaths Mytilus edulis
Alexandrium catenella
DSPSouthern CoastDinophysis acuminata 
D. fortii 
D. caudata 
ASPSouthern CoastNitzschia pungens 

Figure 2

Figure 2: Schematic diagram showing fisheries damage caused by toxic phytoplankton.

4.2 Contamination of aquaculture products

Human illnesses from consuming mariculture products in Korea include PSP, DSP and ASP. Paralytic shellfish poisoning (PSP) is the most serious, it is reported along the southern coast from March to June and its toxicity appears to be increasing. Low levels of PSP have been reported on the western and eastern coasts. The most severe event of PSP occurred in 1986 as a result of consuming mussels attached to the vessels in Kamchon Bay inside Pusan Port and resulted in two deaths. It was caused by Alexandrium tamarense, which occurs mainly from April to June. PSP toxin was found to consist mainly of gonyautoxin (GTX), and a saxitoxin (STX), neosaxitoxin, trace amount of decarbamoyl gonyautoxin and protogonyautoxin (PX), but the level of toxin does not usually exceeded 80μg/100g.

4.3. Impacts of aquaculture on the environment

4.3.1 Inland aquaculture

Physical factors
The build-up of organic materials in sediments as a result of intensive carp cage culture in shallow lakes causes localised eutrophication and occasional algal blooms.

Chemical factors
Table 9 shows chemicals which have been used in fish culture for the treatment of disease. They are mostly supplied in feed for 5 or 7 days so as not to overuse, and harvesting and selling of fish is restricted for 5 to 30 days after treatment, depending on the kinds of chemicals. No harmful impacts have yet been recorded.

Interactions between aquaculture and native species
Two exotic species, large mouth bass (Micropterus punctulatus) and bluegill (Lepomis macrochrius) have caused some disturbance in the food chain of the wild inland ecosystem. Risk assessment has not been carried out, but the native wild species will be replaced by these exotic species.

Social conflicts and aquaculture
Intensive finfish cage culture competes to a limited extent with industry for water resources. Eutrophication in lakes may also affect potable water supplies in some areas.

Table 9. Chemicals used for diseases treatment in the Republic of Korea

ChemicalDose ratePurpose
Oxytetracycline-HCl50mg/kg/dayVibrosis, Streptococcosis; Edwardsiellosis, Furunculosis.
Sulfamonomethoxine100–200mg/kg/dayVibriosis, red pest disease.
Oxolinic acid5–20mg/kg/dayPseudotuberculosis, red pest disease, red spot disease, gill rot disease, Vibriosis.

4.3.2 Coastal aquaculture - finfish and mollusc

Physical factors
The accelerated development of intensive finfish culture in the southern coastal waters of Korea has resulted in self-pollution from faeces and feed residues which accumulate on the bottom sediments. In combination with terrestrial run-off, these result in problems of progressive eutrophication. Increased nutrient levels are high enough in some areas to cause harmful algal blooms and damage to caged fish. Similarly, the accumulated wastes resulting from long periods of shellfish farming in a semi-enclosed bay like Chinhae Bay, have created significant oxygen depletion and an anoxic water mass from the mid-water layer to the bottom layer. Such anoxic conditions in the water have caused mass mortality of cultured and natural organisms since 1989. These problems are expected to continue or intensify in the near future.

Environmental monitoring is being conducted as part of a programme of coastal water quality management in fish and shellfish growing areas. To assess eutrophic levels in the water column and sediment, several environmental parameters have been analysed since 1972 along the whole coastal zone and in major estuaries. In some semi-enclosed bays in southern and western coast, the chemical oxygen demand (COD) and dissolved inorganic nitrogen (DIN) values exceed 2 mg/l and 0.1 mg/l, respectively. This indicates that seawater quality in these areas is generally eutrophic or under the process of eutrophication. The COD and ignition loss of the sediment in the Chungmu-Hakrhim area exceeds 15mg/g and 10% respectively. As a result of these high values, a toxic bloom of Cochlodinium sp. and Gyrodinium sp. occurred in summertime resulting in a mass fish kill. Annual variation of environmental parameters indicated eutrophic levels in waters and sediment of the Chungmu-Hakrhim coast from 1989 to 1992 (Table 10).

Chemical factors
See inland aquaculture

Interactions between aquaculture and native species
Intensive finfish and shellfish culture changes the benthic community due to sedimentation of organic matter. It decreases the species diversity and increases the richness of some species, for example, abundant flounder are found below the long-line oyster culture, and arkshell below seaweed culture.

Table 10. Water quality in Chungmu-Hakrhim Coast from 1989–1992.

Parameter 1989199019911992Water Quality Standard
Water columnCOD (mg/l) mg/l
DIP (μM)0.490.400.530.980.01 mg/l
DIN (μM)4.866.488.625.900.1 mg/l
SedimentCOD (mg/g)15.5918.4318.4216.53 
H2S (mg/g) 
Ignition Loss (%)11.9810.1610.60- 

Social conflicts and aquaculture
Coastal aquaculture operations have faced some competition for land space due to coastal reclamation for industrial and agricultural purposes. The widespread use of hanging rafts to collect shellfish seed in summertime temporarily interferes with navigation.

4.3.3 Coastal aquaculture - seaweed

Few environmental problems were identified with respect to seaweed culture. Some localised decrease in nutrient levels has occurred around dense seaweed culture areas.


5.1 Oyster long-line culture system

5.1.1 Description of oyster long-line culture system (see Figure 3)

Human population pressure has stimulated the development of aquaculture schemes for oysters which are regarded, not as a gourmet dish, but a staple seafood. This has led to the development of various techniques of off-bottom shellfish growing which has increased production many fold over natural levels. Oysters have been cultured on a small scale since the last of the Yi dynasty, nearly a century ago. Even at that time Koreans preferred to eat oysters.

Oyster culture was developed in 1907, the year of the promulgation of law for Korean fisheries. In 1918, 1,425 ha of culture sites were legally licensed with a harvest of 132 tonnes. Hanging culture systems were first employed in the 1930s and developed rapidly in the 1970s and 1980s, with an annual production of 200,000 tonnes from about 8,000 ha of oyster beds. The production per unit area was gradually reduced from a peak of 30 tonnes per ha in 1988 to around 20 tonnes per ha in 1989, due to eutrophication. Long-line oyster culture is becoming increasingly popular, particularly in the south. In addition to the lower initial expense and maintenance costs, long-lines possess the advantage of withstanding winds, waves and currents better than rafts, so it possible to grow oysters in more exposed situations in the open sea where raft culture is not possible. Long-lines are 100m long with an anchor at each end of the line, and sometimes the middle. Floats are spaced 2m apart, but this distance is halved when the ropes are weighed down with oyster rens. Three rens, similar to those used in raft culture, are suspended from the ropes between each pair of floats. The length of the rens is usually 7m, depending on the depth of the water. Rens should not be allowed to touch the bottom at any time.

Figure 3

Figure 3: Schematic diagram of oyster longline culture system in Korea.

5.1.2 The impact of environment on the oyster long-line culture

Nature of impact on culture activity
Coastal population growth, in particular, has been accompanied by the destruction of natural oyster grounds, both intentionally in the course of development of seashore property for other purposes, and unintentionally through domestic and industrial pollution. Marine pollution constitutes a double threat to the oyster culture industry as even where the animals themselves are not harmed they may, due to their habit of filter feeding, concentrate pollutants in their flesh and become unfit for human consumption.

History and extent of impact on culture activity
In recent years, pollution and other factors has threatened oyster production in the south sea of Korea which receives a lot of industrial and domestic wastewater. Pollution effects on oysters are most severe in the south-eastern sea. Since 1981, environmental pollution such as red tides and anoxia have reduced oyster production on the Korean coast, but statistics on the quantities of lost production since 1981 are not clear, with the exception of the loss of 1,301 long-lines due to the Gymnodinium red tide in 1981.

Description of cause of environmental impact on the culture activity
The most important causes of environmental impacts on oyster culture are: the destruction of coastal substrates which hinders the attachment of spat; eutrophication resulting in harmful algal blooms; and direct toxicity of some materials. Oyster spat collection is greatly influenced by water quality which controls the abundance of the phytoplankton community. In eutrophic waters, toxic dinoflagellate blooms have occurred and caused oyster kills for example in Chinhae Bay in the south sea in 1978 and 1981. Sometimes anoxic waters have resulted from persistent seasonal blooms causing oyster kills from late spring to fall when thermal stratification was developed.

Management of environmental impacts

  1. A national budget of around US $ 225,000 has been allocated for the annual water quality and red tide monitoring.

  2. National water quality monitoring has been carried out since 1972 in coastal oyster beds. The major parameters that are checked are: bacteria, PSP, DO, COD and nutrient salts (to assess the eutrophic level) and five heavy metals (mercury, copper, zinc, lead and cadmium).

  3. Regular red tide monitoring, to minimise the bloom damage from March to November, has been in operation since 1981.

Legal framework for the environmental management of aquaculture
In Korea, legal frameworks for environmental management included the declaration of clean zones and the establishment of water quality standards.

  1. Water quality standards were designated by principal environmental policy law for the purpose of assessing the appropriate use of coastal water.

  2. Four areas were designated as clean zones and most pollution inducing activities were not permitted in and around culture areas and sanitary oyster were exported using shellfish sanitation regulations.

  3. Special management of water pollution in the coastal zone was established under the Marine Pollution Control Law, which was enacted in 1977.

  4. Special areas for the conservation of fisheries resources were designated by land use and management law.

  5. Restrictions on terrestrial pollutants intakes to estuaries and coastal embayments by aquatic environment protection law.

The compensation payments which the aquaculturist can obtain, are:

  1. Governmental compensation for the economic loss due to the abnormal environmental changes such as typhoons, and harmful algal blooms.

  2. Non-governmental compensation for the damages caused by the pollution, unexpected oil spills, reclamation and industrial activities.

5.1.3 Influence of oyster long-line culture on the marine environment

Nature of impacts caused by intensive long-line oyster culture

  1. Production of dissimilative faecal organic substances.

  2. Accumulation of dead oysters and the other animals on the bottom.

  3. Accumulation of buoys, nets, ropes etc. On the bottom.

  4. Interference with the direction and velocity of tidal current.

  5. Disposal of oyster shells becomes a problems in coastal areas.

History and extent of impact caused by culture activity
Impacts may date back to the late 1980s because there has been no increase in oyster production per unit area since then. These impacts were localised to the areas of intensive culture and enclosed bays.

Description of cause of environmental impact
Intensive and persistent oyster culture for a long period of time causes:

  1. Sedimentation of organic substances and changes in the benthic fauna and flora. Until the 1960s the major species under oyster long-lines were mollusca and crustaceans with high species diversity. However, this community changed to ascideans, sea cucumber etc, with a low species diversity;

  2. Water-borne eutrophication, resulting from the decomposition of accumulated organic materials. This can act as a reservoir for limiting nutrients such as inorganic nitrogen and orthophosphate by way of regeneration from the bottom sediments;

  3. A deterioration in water quality. For example, a high value of chemical oxygen demand and low unsaturated dissolved oxygen levels.

Management of environmental impacts
Methods of minimising the environmental impacts caused by oyster culture activities include:

  1. Recommend the culturist to keep optimal stocking densities on the basis of environmental carrying capacity to sustain optimal oyster production;

  2. Siting of oyster beds is a prerequisite to the granting of a licence;

  3. Licensing authorities under the fisheries law are to control the potential environmental impacts.

The legal framework for environmental management of aquaculture
Licensing conditions require that the aquaculturists do the following to manage culture beds:

  1. Clean the bed using dredges more than once every three years;

  2. Keep a distance of more than 100 meters between the one licensed bed and another;

  3. Restrict licensed area within 1 to 20 ha for one licensed oyster bed;

  4. Construct one 100 m long-line per 50m2 and the ratio of culture area over licensed area cannot exceed 3–10% of total license area.

5.2 Intensive finfish cage culture system

5.2.1 Description of yellowtail/seabream cage culture system

The juveniles are stocked in floating nylon net cages (Figure 4), ranging from 2 to 50 m2 in area and 1 to 3m depth. Growing for market is done in cages (35 to 100 m2 in area, 3 to 6m depth) made of nylon net. In choosing a location for the cages, factors such as circulation, temperature and pollution must be taken into consideration. The use of cages, both for fry rearing and for growing for market, has been the key to the success of finfish farming and is now being adopted in a number of other types of fish culture. Floating cages combine the advantages of small and large enclosures.

Figure 4

Figure 4: Cage culture systems commonly used in the Republic of Korea

5.2.2 The impact of environment on the finfish cage culture

Nature of impact on culture activity
To date, there have been no significant environmental impacts on aquaculture, except the damage caused by dinoflagellate blooms in Chinhae Bay.

History and extent of impact on culture activity
Environmental changes, such as unexpected effluents containing toxic chemical materials and harmful algal blooms, have caused some fish mortalities in Chinhae Bay since the 1980s. Most of these impacts were localised in enclosed bays distributed in the south-eastern coast of Korea, which have received a lot of industrial effluent since the 1960s. However, the number of culturists affected and the economic value of losses were not computed.

Description of cause of environmental impact on the culture activity
Urban/industrial development has led to coastal pollution, which interfered with the collection of fry and juveniles for culture due to the reclamation of the nursery grounds

Management of environmental impacts
See long-line oyster culture.

Legal framework for the environmental management of aquaculture
See long-line oyster culture.

5.2.3 Influence of finfish cage culture on the environment

Nature of impacts caused by culture activity
In the intensive finfish cage culture, the following impacts were noted:

  1. Waste food and dissimilative faecal organic substances sedimented on the sea bottom causing eutrophication of surrounding waters;

  2. Accumulation of solid wastes (such as buoys, net, rope etc.) on the bottom sediments;

  3. Interference with the direction and velocity of tidal currents.

History and extent of impacts
The affected area is localised to the intensive finfish culture growing area in Chungmu and its vicinities. There was no occurrence of toxic red tides in these areas before intensive cage culture began. In 1992, culture finfish worth of US $ 13.7 million were killed by a toxic dinoflagellate bloom which occurred in August.

Description of cause of environmental impact
Intensive, large-scale culture systems have caused environmental change such as sedimentation of organic substances. After decomposition, a high proportion of the inorganic nutrients contained in the organic material is released into the overlying waters. This nutrients enrichment finally induces algal blooms.

Management of environmental impacts
See long-line oyster culture. Additionally, fish cages should be managed to mitigate the pollution load and take into account environmental carrying capacity. In Korea, the following measures are also being undertaken:

  1. Research projects on selective breeding of resistant species and fast growing fish;

  2. In depth studies of drifting and low phosphorus feeds and appropriate stocking densities.

Legal framework for environmental management of aquaculture
Under licensing and management regulations, the finfish aquaculturists should carry out the following activities:

  1. The seabed must be cleaned with dredges more than once every three years;

  2. A distance of more than 300 meters must be kept between one licensed site and another;

  3. License areas are restricted to 0.5 to 10 ha for one finfish license culture bed;

  4. Each cage should be 25m2 (5m long, 5m wide and 5m depth);

  5. Cage area will not exceed 5–20% of the total licensed area;

  6. All finfish culture should have a license from the municipal authorities.


6.1 Prevention and cure of the detrimental effects to aquaculture of man-made changes to the environment

6.1.1 Coastal aquaculture

Industrial, human and agricultural waste
The coastal ecosystem is large and once polluted it will be difficult to decontaminate. Further work is required to identify the present status of coastal pollution and develop a more scientific approach to pollution monitoring and control techniques, in order that accurate and precise coastal ecosystem pollution assessments can be made. Major countermeasures planned by administration systems are as follows:

  1. Classify the coastal area into three classes based on present water quality, and control water quality according to the purpose such as fisheries, recreational, agricultural and industrial use;

  2. Set ambient water quality standards and control industrial and municipal effluent into the coast;

  3. A national seawater quality monitoring system which divides the whole coastal region into 6 segments. In 1991, 270 sampling sites were measured to improve the monitoring efficiency;

  4. Expansion of basic environmental facilities: Investment of US $ 3.1 billion during 1992– 1996 to construct basic environmental facilities such as sewage treatment facilities, industrial wastewater treatment plants and excretion treatment facilities;

  5. Environmental Impact Assessment systems: Execution of a marine environmental impact assessment process over all proposed coastal development activities to protect the environment and fisheries resources from adverse effects;

  6. Designation of special conservation sea areas: Designation and management of 934 km2 of semi-enclosed coastal areas since 1982 as “Coastal site for special management of pollution”. Also to designate 29 Stations as Fisheries Resources Conservation Areas to restrict development activities (such as land reclamation, industrial complex construction and dredging) in these waters.

Phytoplankton blooms
The following countermeasures have been adopted to protect aquaculture and fisheries from the adverse effects of red tides:

  1. Legal regulatory measures to reduce and treat the effluents of industrial, domestic and wastewaters to control the COD load;

  2. A biweekly monitoring system to detect red tides and alert fishermen when toxic species are identified;

  3. Predict red tide occurrences, their expected duration and the dominant species involved;

  4. Appropriate farm management measures to reduce the damage caused by red tides, e.g. stop feed inputs; remove or sink cages away from affected waters; and rapid harvest of culture products;

  5. Recommend measures to the Ministry of Environment to reduce nutrient inputs in coastal areas.

Contamination of aquaculture products
Potential health risks from contaminated shellfish and fish products are minimised by the following measures:

  1. Special alerts when some shellfish poisoning dinoflagellates (e.g. Alexandrium sp.) are identified, and interdict harvesting and selling when PSP toxin levels exceed the standard of 80μg/100g.

  2. Regulation to interdict culture and harvest of marine organisms when the concentration of mercury, copper, lead and chromium in sea water exceed 0.005 mg/l, 0.01 mg/l, 0.1 mg/l and 0.05 mg/l, respectively.

  3. Regular analysis of heavy metals in seawater, sediment and marine products.

6.2 Prevention and cure of the detrimental effects of environmental changes caused by aquaculture activities

6.2.1 Inland aquaculture

Physical factors
Regulatory measures to prevent pollution by inland fish farms include:

  1. Enforced water quality standards and effluent controls in ponds and lakes to minimise the dangers of toxic chemicals and heavy metal residues;

  2. A gradual reduction in the number of culture cages;

  3. Most lakes are designated as fishery resource conservation areas.

Chemical factors
The amount, chemical species and dose rate of chemotherapeutants used in aquaculture should conform to the guidelines made by NFRDA.

Social conflicts and aquaculture
Algal bloom in reservoir for supplying drinking water have caused some conflicts.

6.2.2 Coastal aquaculture

Physical factors
Regulatory measures to limit damaging impacts of coastal aquaculture include:

  1. Enforced coastal water and effluent quality standards;

  2. Cleaning of the seabed, particularly in finfish and shellfish culture areas has reduced loads of sedimented organic material and enhanced aerobic decomposition activities;

  3. Interdict the flow of domestic and industrial sewage into aquaculture areas, especially coastal areas designated as clean zones or fisheries resource conservation areas.

Chemical factors
See inland aquaculture.

Social conflicts and aquaculture
Coastal reclamation is completely controlled by the government and is prohibited in the fisheries resource conservation areas to alleviate conflicts with local aquaculture and fisheries. Central and provincial government monitors the numbers of hanging rafts used for mollusc seed collection in order to reduce interference with navigation.


7.1 Biotechnological development

  1. Polyculture based on the food chain and the energy flow in the coastal ecosystem (funded).

  2. Sea farming and husbandry for mass production of commercial species (funded).

  3. Selective breeding and hybridisation of finfish and shellfish (funded).

  4. Genetic study of bastard halibut to produce pseudomale for all female population and its genetic control (funded).

7.2 Development of efficient culture system

  1. For off-shore finfish culture, research of a wave resistant culture systems has been undertaken as part of a special national project since 1993 (funded).

  2. Efficient filtering technology for high stocking culture density in enclosed recirculating tank systems (funded).

  3. Technical research for the acclimatisation of pelagic finfish for indoor culture (funded).

Annex II-9


K. Roger and K. Vattanathem, Ministry of Agriculture-Forestry, Vientiane.

Pond culture of freshwater fish is an important form of aquaculture production in Lao PDR.


This report provides an overall assessment of environmental issues related to aquaculture in Laos. No serious environmental problems created by aquaculture or impacting on aquaculture have yet been recorded. Culture practices of semi-intensive fish ponds at selected sites in Laos are recorded and presented. The positive impacts of aquaculture on human health and hygiene, and in combating drought, have been noted and reported. The Government is cautiously taking further steps to prevent damage to the environment through their national policies.


This country report provides background information regarding the existing impact of aquaculture on the environment in Laos and vice versa. The topic assigned to Lao PDR for in-depth study was “pond culture”, the species involved being mainly the Asiatic carps, common carp and tilapia. Due to the limitations of movement, funding and lack of a well organised data collection system in Laos, a few pond culture sites were selected in the Vientiane prefecture (Central Plain) and also in Xieng Khouang Centre (Highlands) and observed for data collection. The observations made at these sites can be extrapolated to depict the situation over the country as a whole.


In the animal protein sector of the fisheries sub-sector in particular, the role of aquaculture is gaining more importance and its contribution is increasing in both tonnage and percentage of total fisheries production. As has already been indicated, exact statistics on fish production in Laos PDR are not available, there are only estimates based on written and verbal reports received from the Government and fish farmers. The increase in aquaculture activities in ponds and rice fields is, however, evident. At the same time, there has been a decline in the fisheries of the Mekong River, with an estimated 20% decrease in fish landings at major centres in the Vientiane Prefecture, Savannakhet and Pakse also reported. The decline in fish stocks in the Mekong is mainly due to uncontrolled overfishing and the use of destructive fishing methods on the one hand, and the large scale capture of broodfishes during their spawning season on the other.

Map of Lao PDR.

Map of Lao PDR.

The revised estimates of aquaculture production up until June 1992 were around 10,140 tonnes, about 34.5% of the total fisheries production (estimated at 29,405 tonnes). In aquaculture production, the area under pond fish culture has increased from about 6,000 ha to 8,000 ha. Farm management has also improved so overall production estimates have gone up from 1,830 tonnes to 3,600 tonnes, which is more than 12.2% of total fish production (increased from an estimated 6.8% in 1990). Similarly, in rice-cum fish culture, the total area was estimated at 418,000 ha in 1992, compared with 416,000 ha in 1990. This increase was mainly due to improvements in irrigation systems and culture practices. Fish production from this source was estimated at 6,540 tonnes in 1992 (over 22.2% of total fish production) compared to 4,400 tonnes in 1990 (16% of total fish production). Cage culture in Laos is only practised on a very limited scale.

The major species cultured are the exotic Asiatic carps (Indian and Chinese major carps), common carp and tilapia. The common indigenous species are Probarbus jullieni, Morulius chrysophekadion, Trichogaster pectoralis, Osphronemus goramy, Osteochilus prosemion, Puntius gonionotus, Anabas testudineus, Cirrhinus microlepis, Notopterus chitala, Notopterus notopterus and Pangasius pangasius.

Exotic carps are mainly cultured in ponds whereas indigenous fish are mainly cultured in rice fields, along with some exotic species such as carp and tilapia. The culture areas (ponds and rice fields) are scattered all over the country but, in the colder highlands, common carp, tilapia and some Chinese carps are grown in ponds and rice fields along with indigenous species to a limited extent.

Information on species-wise production is scanty, almost all of the species cultured are marketable and the Laotian population in general is not too selective, although some species are more in demand than others.

Aquaculture inputs are mostly good fish seed, nets and fish breeding materials for seed centres, which are all easy to obtain and are purchased by the farmers. Some farmers produce seed not only for themselves but also for sale to others.

As already stated, the total area in this land-locked country devoted to aquaculture is estimated at 8,000 ha of fish ponds. This is likely to increase in the future in view of the current national drive to construct more fish ponds in drought affected areas. Similarly, the estimated area of irrigated rice fields is also likely to increase from the present 18,000 ha which has contributed to increases in fish production. The adoption of scientific fish culture techniques in rice fields will also increase fish production from the rice fields. Scientific fish culture techniques include digging trenches, using proper stocking densities of selected species, manuring the fields and feeding the fish.

Government policy has allotted a high priority to aquaculture development as it is possible to promote this with locally available low-inputs. Legal steps to regulate aquaculture development are not considered applicable due to the slow growth of the industry and the fact that only traditional and semi-intensive practices have been adopted so far. However, proper laws are being enforced and a new legal basis is still being framed to prevent further destruction of capture fisheries.

The Government (Ministry of Agriculture and Forestry) has enforced the following regulations to conserve and manage capture fisheries in Laos:

The forestry department has introduced the following laws to control deforestation:


The environmental issues related to aquaculture are not posing any serious problems at the moment and possibly will not in the near future either. This is because intensive aquaculture development, which is often the cause of major environmental hazards, is still a long way off as is any large-scale industrial development. At the same time, the Government is fully aware of these dangers and also the need to control the abuse of pesticides or insecticides in agriculture in Laos. The Government has prohibited the large-scale use of pesticides, like systemic pesticides and organophosphates, and is advocating limited use of easily degradable pesticides like Furadan and Sevin. The agricultural policy of the Government (MAF) is to encourage the growing of more resistant varieties of paddy which would not need much use of pesticides. Some stray cases of health hazards, like partial paralysis, have been reported where farmers have not followed all the precautions when handling the pesticides. However, environmental problems caused by the use of agrochemicals are noted only in some areas.

The siltation of water bodies and irrigation channels as a result of soil erosion caused by deforestation is also being carefully monitored by the Government, by checking shifting cultivation practices and the logging of forests. A notable positive impact of aquaculture is seen in national policy which encourages the digging of ponds in drought affected areas, mainly to use the ponds as water reservoirs for irrigating crops but also for growing fish. In general, fish culture helps to control diseases caused by mosquitoes and snails and improves the hygienic condition around the households by proper integration.

Under the Regulation of Water Resources Management in Lao PDR, issued by the Prime Ministers Office, the MAF is given responsibility for monitoring water quality in some of the major river systems and reservoirs. The results of water quality monitoring from 1990 – 1992 are summarised in Table 1. There are no major industrial units where effluents cause any serious environmental hazards, particularly to aquaculture. Most of the waterbodies used for aquaculture are saved from inflows of pesticides and deforestation and shifting cultivation is being strictly controlled by Government laws to reduce the problem of soil erosion. Farmers are being encouraged to keep their ponds clean and the fishes stocked are known to help in controlling the mosquito population.

There are no perceptible negative effects of exotics on indigenous species. However, the uncontrolled population of tilapias, combined with the problem of runting and wild hybridisation between the species O. niloticus and O. mossambica are considered a negative impact.

Table 1. Water quality monitoring results for aquaculture, 1990–1992.

Temperature (°C)22.427.430.720.228.632.421.027.532.7
Total suspended Solids (mg/l)47.0141.0260.015.3246.4892.00.1108.22044
Conductivity (μS/mm)10.023.766.60.632.788.611.228.760.0
Calcium (meq/l)0.2160.5180.7560.2410.8981.700.4221.0962.40
Magnesium (meq/l)0.0340.2110.3840.0270.3580.6980.1600.4711.315
Sodium (meq/l)0.3720.7792.0400.0881.2723.440.161.1391.720
Potassium (meq/l)0.0340.0870.2220.0350.2671.1850.0400.1080.260
Alkalinity (meq/l)0.6090.8011.1360.5091.2272.1550.1611.4083.287
Chloride (meq/l)0.2490.9392.8420.1481.3173.6840.3371.1464.043
Sulphate (meq/l)0.0340.4811.9080.0610.3840.9150.1350.3931.055
Total Iron (meq/l)0.1430.4850.7090.0250.4962.5480.0350.3991.209
NO3+NO2 N (mg/l)0.1430.2350.7090.0190.3681.5260.0080.2140.665
NH4-N (mg/l)0.0080.0600.2390.0060.3732.0040.0280.2541.347
Total N (mg/l)      0.1420.2480.461
Orthophosphate (mg/l)0.0010.0106.000.0010.0520.1220.0220.0770.225
Total Phosphorus (mg/l)0.0080.0530.1070.0010.0520.1220.0220.0770.225
Silicon (mg/l)0.9502.4505.8002.4004.3036.7002.5004.3838.100
Dissolved oxygen (mg/l)0.0841.3742.7101.3212.6364.0200.7102.3923.500
COD (mg/l)


5.1 Pond fish culture in Lao PDR

This study is confined to a few selected districts of two provinces in Lao PDR, the Vientiane Prefecture and Xieng khouang. The information is mostly collected from farmers and fish farm managers.

5.1.1 Vientiane Prefecture

Nong Teng Fish Farm
The total pond area of 12 ha was divided into 7 ha of stocking ponds, 2 ha of broodfish ponds and the remainder are nursery and experimental ponds. The species cultured are Asiatic carps (3 Chinese carps and 3 Indian major carps), tilapia, Puntius gonionotus, and also local species under experimental study such as Probarbus jullieni and Cirrhinus microlepis.

The production in 1992 was 2.3 t/ha and 1 million fish fry and juveniles were produced. The farm is well-managed and under the supervision of the Fisheries Section of the Livestock Veterinary Department. No adverse affect on the environment from this fish farm has been reported.

Mr Khoun (Sikhottabong District, Nahae Village) - Fish Farmer
The total pond area is 1.5 ha with 4 stocking ponds and 5 nursery ponds. The main species cultured are common carp, tilapia, Puntius gonionotus and Chinese and Indian carps. In the initial stages, this farmer practised only rice-fish culture, but in recent years he has converted most of the rice fields into fish ponds. He produces fish seed for his own ponds and supplying to neighbouring farmers. The marketed fish production of the farm was 2.5 t/ha in 1992 and 100,000 fish fry and fingerlings.

No adverse environmental effects were seen, rather the area is more hygienic, well maintained and integrated with fruit trees and livestock to a limited extent.

Mr Sutchai (Sikhottabong District, Nonkeo Village) - Fish Farmer
The total pond area is 0.5 ha with three stocking ponds and three nursery ponds. The fish culture system is integrated with poultry and vegetable crops. The main species cultured are common carp and tilapia and about 150 local chicken and about 70 local ducks are raised every year and cucumber is grown on the pond dike and in adjacent rice fields during the dry season. The annual production is around 2 t/ha/year of marketable fish and about 50,000–70,000 for fish fry and fingerlings. About 300 kg of live poultry and about 200 kg of cucumber were obtained last year.

Technical aspects of the farm need to be improved as it seems to be overstocked.

No adverse environmental effects have been seen, rather the area is more hygienic, there is good water supply from the stream and the animal wastes and by-products are well utilised.

5.1.2 Xieng Khouang Province

Khangpho Fish Farm (Muongkhoun District)
This is a provincial fish seed farm. The total pond area is 7 ha with well designed ponds and a hatchery. The production capacity is around 10 t/year from 5 ha of stocking ponds and around 2 million fry and fingerlings can be produced. The cultured species are three Chinese carp, common carp and tilapia. The system of culture is semi-intensive polyculture and the farm produces mainly fish seed for supply to farmers throughout Xieng Khouang Province. No adverse effects on the environment have been seen.

Mr Oun Fish Farm (Muangkham District, Ban Huok Village)
The total area of ponds is 2.5 ha with 3 stocking ponds (0.5 ha) and 4 plots of rice field (2 ha). Two kinds of fish culture are carried out namely fish-cum-pig culture and rice-cum-fish culture. The species cultured are common carp and tilapia. Production is 1.5 t/ha/year in pig-cum-fish culture whereas about 200 kg/ha/crop is produced in rice-fish culture. No adverse environmental effects have been seen.

Mr Salivanh Fish Farm (Muangkhan District, Ban Bal Village)
The farm is an integrated fish-livestock and crop production system. In a total area of 3.5 ha (fish pond 1.5 ha and rice field 2 ha), the fish ponds are integrated with pig raising. The species cultured are common carp, tilapia and Chinese carps. The production was 1.8 t/ha of marketable fish; and 600 kg of live pig in 1992 from the ponds. From rice fields, 300 kg of fish were produced and 5 tonnes of paddy in 1992. It is a semi-intensive culture system. No adverse environmental effects were reported.


The national priority is quite clear in not allowing any major environmental problems to be caused by aquaculture development. It is planned to develop aquaculture with positive effects on the environment.


The future direction of aquaculture development in Lao PDR will focus on two aspects:

  1. Improvement of rural nutrition and economic improvement by changing traditional culture systems to more scientific systems, up to semi-intensive levels (using easily available local inputs).

  2. Commercial fish culture to meet the fish demand in urban areas and for export of fish and fish products to earn foreign exchange.

In order to achieve the above two objectives, the gradual expansion of national infrastructure to support extension and adaptive research activities (both facility-wise and upgraded manpower-wise) would be promoted. Naturally, this development will carefully monitor environmental issues with the support of national policy.

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