Oyster (gul)

Gul, also called gul-jogae and written in older texts as seokhwa ("stone flower"), is the oyster. The Encyclopedia of Korean Culture names three main Korean species: the Pacific oyster (cham-gul), which is farmed; and the rock oyster (bawit-gul) and a third species, beot-gul, which are gathered wild. Oysters are the most common shells in Korea's prehistoric shell middens, and the 16th-century gazetteer Dongguk yeoji seungnam lists them as a local product of seventy districts in seven provinces.

No record shows when Koreans began to farm oysters. A survey from around 1908 found small-scale culture at the mouth of the Seomjin River, and Japanese operators started farms in the following years using bamboo and pine stakes. Hanging culture, with oysters grown on lines suspended in the water, appeared in the 1930s, and the industry took off in the 1950s, when the government promoted oysters to help struggling seaweed farmers. Raft and longline methods followed, and by the 1970s suspended culture was booming along the south coast around Tongyeong (then Chungmu).

Tongyeong in South Gyeongsang remains the center of the trade: the Encyclopedia of Korean Culture credits it with about 30 percent of national production, and the city holds an annual oyster festival. Oysters are eaten raw as saeng-gul or cooked into rice (gul-bap), porridge, soup and pan-fried gul-jeon, and they are also salted as jeotgal; eoriguljeot is a lightly salted version dressed with chili. More than half the national harvest is eaten fresh at home.

• Exceptionally rich in zinc and vitamin B12: USDA data list about 16.6 mg of zinc and 16 µg of vitamin B12 per 100 g of raw Pacific oyster, along with selenium and iron.
• Raw oysters carry real risk: CDC says most vibriosis comes from eating raw or undercooked shellfish, particularly oysters, and lists liver disease, diabetes, cancer, immune suppression and acid-reducing medicines among the risk factors. CDC also notes oysters can carry norovirus when grown in contaminated water.
• Who should avoid them raw: The FDA advises pregnant women, young children, older adults and people with weakened immunity to avoid raw oysters, even ones treated after harvest, and to cook seafood thoroughly.
• Low in mercury: Oysters are on the FDA/EPA "Best Choices" list.
• Shellfish allergy: Oysters are mollusks. U.S. law's major-allergen list names crustacean shellfish rather than mollusks, so mollusks may not be called out on labels the same way; anyone with a shellfish allergy should ask an allergist which kinds to avoid.