Oyster capture-based aquaculture in the Republic of Korea
Kwang-Sik Choi
Cheju National University
Jeju, Republic of Korea
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Choi, K.S. 2008. Oyster capture-based aquaculture in the Republic of Korea. In A. Lovatelli and P.F. Holthus (eds). Capture-based aquaculture. Global overview. FAO Fisheries Technical Paper. No. 508. Rome, FAO. pp. 271–286.
SUMMARY
Oysters are considered to be the most important molluscan shellfish in the aquaculture industry of the Republic of Korea, which, in 2005, produced 251 706 tonnes of oysters. In the Republic of Korea the Pacific oyster, Crassostrea gigas, is widely cultured along the southern coast where a number of small, shallow bays (mostly <10 m in depth) are protected by numerous islands. Oysters are intensively cultured in these bays with a longline suspended culture system. The Korean oyster industry uses mainly wild-caught oyster spat as seed. This is collected from mid-summer to early fall. Oyster spat that settle on the strings undergoes 7–9 months of hardening in intertidal areas. After the hardening period, the oysters are relocated to a grow-out field in the middle of the bay. The market-size products are harvested during late winter and mid-spring following a grow-out period lasting 9–11 months. Approximately 3 400 families are engaged in the oyster longline culture industry on the southern coast, with 22 000 full-time employees in 2005.
INTRODUCTION
The modern oyster culture technique was introduced to the Republic of Korea at the end of Nineteenth century from neighboring Japan. According to the National Federation of Fisheries Cooperatives of Korea, the first oyster culture licence was issued in 1907 and in 1918 approximately 133 tonnes of oysters were produced from 1 425 hectares. Culture techniques in the early Twentieth century were rather primitive and limited to bottom culture in intertidal areas of inner bays using rocks or wooden poles as substrates for seed collection and subsequent grow-out. In the 1960s, modern suspended culture techniques using longlines and rafts were introduced and the culture area subsequently expanded from the intertidal area to deeper waters offshore. Owing to this technical innovation, an estimated 53 327 tonnes of oysters were landed in 1963, an approximate 7 fold increase from the previous year’s landings of 7 036 tonnes. In 2005, approximately 251 700 tonnes of oysters were produced from 8 042 hectares.
Table 1 lists the oyster species occurring in Korean waters. According to Min (2004), 14 species of oyster have been identified in Korean waters, although only Crassostrea gigas is extensively used in the oyster industry. Ostrea denselamellosa, a larviparous flat oyster species, has been cultured in tidal flats on the southwest
Table 1
Oyster species in Korean waters
Source: Min, 2004
coast using rocks and used tires as substrate. Crassostrea ariakensis is an estuarine species commonly occurring in low salinity environments. Due to its fast growth rate and size, e.g. achieving 100–150 mm in shell length within 2–3 years after hatching, small-scale aquaculture has been attempted using a suspended longline system off the southwest coast. Several species of oysters are also found in Jeju Island, located on the southernmost part of the Korean peninsula, although none of them are currently utilized in the oyster industry (Table 1). Although several species of oysters found in the country are potential candidates for the aquaculture industry, only the Pacific oyster (Crassostrea gigas) is extensively farmed. Most of the Korean oyster landings come from small bays on the south coast where Crassostrea gigas is cultured using the suspended longline system. In contrast, wild oysters are also harvested commercially on the west coast where they are found on rocky substrates on tidal flats (Figure 1).