Key words: coastal aquaculture, Korea, marine fisheries
Korean fisheries have had a long history due to its geological profiles. Korean peninsula is surrounded by the east, west (Yellow Sea) and the south sea. Various types of seafood have been caught or cultivated under different environmental conditions in these three coastal areas. The Korean government as well places large efforts to explore the fishing grounds in order to meet the market demand for seafood.
Population growth and high demand for the seafood sharply increased the quantity of production until the 1990s. Total fisheries production increased in 2005 (2,714,050 metric tons) compared with the total production in 2004 (2,519,101 mt). The value of production in 2005 has also increased by 6.3 percent. Total fisheries production is composed of all types of catches from distance fishing, coastal, aquaculture and inland fishing, though excluding the quantity of importation (Fig. 1).
However, recent changes in diets and food palates among younger generation have directly or indirectly affected the size of seafood market. Based on a market survey, only major fisheries could cope with these changes. But the rest of the smaller industries struggle with the changes in market demands. Based on this trend, fisheries industry has to consider terms of structure and production as well as marketing strategy to further understand future market demand.
Although aquaculture technology for live fish production significantly improved during the 1980s and the government was aware of the important role of aquaculture production replacing the shortage of coastal catches, current situation of aquaculture industry doesn't look promising to supply the good quality and enough quantity of products to the market. Recently, the aquaculture industry has been facing difficulties not only because of water pollution, typhoon and red tide but also due to the opening of fisheries market under the system of World Trade Organization (WTO).
Status of Korean Aquaculture
Brief History of Aquaculture
Coastal aquaculture is the most active and predominant type of mariculture in Korea. It has been rapidly developed since the last 30 years in the Korean sea and the major species had changed during the past 10 years as seaweeds culture (Laver, Porphyra tenera, Sea mustard, Undaria pinnatifida) used to be the main species of mariculture during 1960s, so as shellfish farming (Mussels, Mytilus edulis, oyster, Crassostrea gigas, arkshell, Scapharca brogtonii) during 1970s. Meantime, breeding and hatching technique has been set up to some marine fish, red sea bream (Pagrus major), flounder (Paralichthys olivaceus) as well as black rockfish (Sebastes schlegeli) during 1980s. Since then, marine fish farming has become the most rapidly growing industry and economically profitable, although a family-run business in Korea. During the 1990s, the production of flounder and black rockfish (Sebastes schlegeli) has sharply increased and led the live fish supplies to the seafood market.
Techniques of mass production for few marine finfish species were completely stabilized during these times and industry developed separately from hatcheries, grow-out production to the associated industries such as, feed manufacturing, farm construction and live-fish transportation etc. As market demand grows, more production but lower costs of fry supplies were ineludible direction to the industries. In consequence, more fry production units have been built up along the south coast until 1998.
Total coastal line in Korea peninsula is 11,542 km along with 3,000 islands. Three typical geographical profiles are being shown as follows:
- East coast (dong hae an) shows a straight landscape. Mountainous land sharply slides down to the seaside and water depth drops 100m within 500m away from the beach. Warm water from Tsuhima current and cold water current from Liman confronts around 37°N, where there used to be an active fishing ground. However, aquaculture in this coast is not well developed because accessibility for land use for inland-farm is not sufficient and it also has high wave for cage culture.
- South coast (nam hae-an) is archipelagic and most islands are located in this area. Strong currents, mainly influenced by Tsuhima is dominant as water depth is relatively shallow (20-50 m with 1 km away) compared with east coast. All types of aquaculture have been placed in this area and is known to be the most active place for aquaculture since 1960.
- West coast (The coastal line of Yellow Sea, seo hae-an) is also archipelagic, even mud flat is well developed along the west coast. The tidal flux is recorded as 5 to10 m during the day. Landscape along the west coast is also flat and muddy containing 50-70 percent of clay. Shellfish and some crustacean are actively cultivated in this area.
Environmental Conditions for Aquaculture
Having typical four seasons in a year, fluctuation of water surface temperature is shown in Table 1. Salinity surrounding Korean peninsula ranges from 31.4-34.4 percent all-year round and salinity in the west coast is lower than the east coast.
Most cage culture takes place in the embayed sites where
- water depth is below 50 m
- have no strong wave action
- can escape from typhoon (3 to 5 times during July to August).
However, the recent problem faced in this type of farming area is water pollution and red tide. Although no direct evidence of using moisture pellet to the farm causes water pollution and red tide, the frequency of outbreak of red tide is increasing along the coastal areas. It does affect the hatching process, which requires high quality of seawater intake from seashore as the most hatcheries are located along the coastal area.
Licensed Area for Aquaculture
Licensed area for aquaculture in 2005 has reported to be 124,688 ha and 1,822 ha for fish culture. The biggest land area are allotted for seaweed culture as 69,503 ha and 2,149 farms, respectively, and then shellfish (Fig. 2).
The major portion of marine aquaculture production is seaweeds, next is shellfish. However, we have to take notice that fish production is increasing rapidly. In 2005, it was about 81,000 tons (Table 2). Inland aquaculture production is different from that of marine aquaculture. In inland aquaculture, fish production is the biggest component, being nearly 16,000 tons in 2005. In fish culture, flatfish culture is the primary industry, and then rockfish, seabream and mullet in that order. In 2005, eel is the largest species produced in inland aquaculture, next is trout, cat fish and carp. However, carp and yellow-tail production is decreasing rapidly.
Aquaculture in the sea has developed differently because of three coastal types.
East coast. Because of simple coastal line and tough wave action, no active aquaculture has taken place in this side of coast. Flatfish (P. olivaceus) culture on the land-based tank is the main species near southeast coast and scallop (Patinopecten yessoensis) farming is in the northeast coast.
South coast: Archipelagic environment makes this side of coastal environment ideal to install the cages. Particularly, KyoungNam and ChonNam province are traditionally key areas to produce the variety of seafood. These areas record the highest aquaculture production through all types of aquaculture, such as cages for bream and rock fish, inland based grow-out farm for flatfish, long-lining for oyster and mussel. The species cultivated are listed as follows:
- - Finfish: rockfish (S. schlegeli), red sea bream (Pagrus major), Striped perch (Oplegnathus fasciatus), Black porgy (Acanthopagrus schlegeli) and seabass (Lateolabrax japanicus) in the cages and flatfish (P. olivaceus) in the land based on-growing tank.
- - Shellfish: oyster (Crassostrea gigas), mussel (Mytillus galloprovincialis), cockleshell (Tegillarca granosa), arkshell (Scapharca brogtonii), pearl oyster (Pinctada fucata martensii) and abalone (Haliotis discus hannai) etc.
- - Seaweeds: laver (Porphyra tenera), sea mustard (Undaria pinnatifida) and sea weed fusiforme (Hizikia fusiforme) etc.
- - Others: Sea squirt (Halocynthia roretzi)
West coast. shrimp (Penaeus japonicus, P. chinensis) and Chinese mitten crab (Eriocheir chinensis) is mainly cultivated in Taean, ChungNam and Sinan, ChonNam. Rockfish (S. schlegeli), black porgy (Acanthopagrus schlegeli), seabass (Lateolabrax japanicus) and river puffer (Takifugu obscurus) is also produced in this region. Shellfish culture such as short-necked clam (Ruditapes phillippinarum) and oyster (Crassostrea gigas) is also active in the coast. Currently, the use of the earthen pond for the finfish culture has been tried and it obtained positive results.
Cheju province. Warm and good quality of water supply, in particular, bore water available from the coast are the advantages of this island. Flatfish (P. olivaceus) production is mostly competitive for Japanese market after being recognized as the best quality fish.
Future Directions of Korean Aquaculture
The integrated aquaculture management has created an alternative plan in order to overcome many problems. In the integrated aquaculture management, the scope of aquaculture ground extends to open areas where it was previously not included, until recently.. The aquaculture ground is divided into three subdivisions: the areas for land-based aquaculture, the polytrophic aquaculture, and the offshore aquaculture. Land-based aquaculture, systems are principally positioned on the upper parts of inertial zone and the locations over the inertial lines. In the former system, culture waters are exchanged by the gravity which was caused by the tidal movement, while exchanging with an aid of electronic power in the latter system. Cultures of tank, pond, raceway, silo, and recirculation are available. Urban aquaculture also belongs to this management. The polytrophic aquaculture basically focuses on the ecosystem-based aquaculture, where two different trophic organisms are maintained in a given aquaculture ground. In practical sense, systems for algal seaweeds and bivalves are alternatively deployed.
The seaweeds in the polytrophic system utilize nitrogen compounds from metabolic activity of the bivalves, otherwise, the compounds are accumulated on the ground as an organic pollutant. The offshore aquaculture is the most advanced technology for finishing and shell fishing. One of the biggest problems confronting the successful introduction of the offshore aquaculture is how to overcome the high-surface energy which can physically damage cages in the open environment. There is less likelihood that the cage will be damaged by physical energy, even during typhoons, for the cage is submerged. The submerged cage can eliminate visual impact coming from deployment of cages in the coastal waters. The most outstanding advantage of the offshore aquaculture is the aquaculture activities.
Index of Images
Table 1 Variation of Surface Water Temperature Monitored for 30 Years at Three Coastal Sides in Korea
Figure 1 Fisheries Production and Its Value in 2005
Figure 2 Aquaculture Area by Species in 2005
Table 2 Aquaculture Production by Culture Species
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