Gim (food)

Production of gim in Jeolla and Gyeongsang Provinces is reported in books from 15–16th century, including Sinjeung Dongguk Yeoji Seungnam|Revised and Augmented Survey of the Geography of Korea (1530) and Gyeongsang-do Jiriji | Geography of Gyeongsang Province (1425). In these books, gim is mentioned as a regional delicacy.[19][20]

Gim cultivation is the oldest aquaculture in Korea and there are several stories from oral tradition about its origins.[21] One version tells the story of an old lady in Hadong, South Gyeongsang Province who discovered a log covered in gim floating down the Seomjin River. This inspired her to cultivate the gim on upright support poles made of bamboo.[21] Another legend says gim was named after Gim Yeoik (1606–1660)―the first person to have cultivated gim after seeing a drifting oak branch covered in it. Yeoik's story takes place on Taein Island which is located in the mouth of Seomjin River in Gwangyang, South Jeolla Province, during the reign of King Injo (1623–1649).[21] Gim cultivation continued to expand and spread throughout the southern coastlands of Korean Empire (1897‒1910).[21]

Early cultivation methods using bamboo or oak sticks were eventually replaced by newer methods that utilized nets,[21][22] developed in the 19th century by a fish harvester who was inspired by gim that grew naturally on fish fences installed in the tidal waters of Wando, South Jeolla Province. Floating rafts have been used for mass production since the 1920s.[21]

P. yezoensis is the most commonly cultivated species of gim, followed by P. tenera.[28] Wando, South Jeolla Province is the main production area for cultivated gim. Gim cultivation is traditional to the Southern parts Korean peninsula—the Honam, Yeongnam regions, and Jeju Island—as the algae only grow in the oceans around the southern part of Korean Peninsula.[29] However, due to increases in sea temperature, gim can now be cultivated further north and has spread to the Hoseo region in central South Korea.[29]

Gim produced during the winter in estuaries or the brackish water zone, with 1.024 ‰ salinity, is said to be the most delicious.[4][22] Seeding begins in autumn—between September and October—and multiple harvests can be taken from a single seeding throughout the winter months. The algae are known to grow well in sea water when temperatures are between 5–8 °C (41–46 °F). Gim that has been grown for 50 days is considered best for consumption, as the color and flavor are at their peak.[22]

Two main cultivation methods are used in contemporary gim farming: traditional "racks" method used for high quality gim that is similar to naturally grown laver, and the "floating rafts" method used for mass production.[29] Racks type gim, similar in quality to naturally occurring laver, is currently produced in some areas of Wando, Sinan, Gangjin, and Jangheung; however this type of gim is grown in fewer than 100 farms across the country. The number of farms that use the rack method has been declining due to high production costs, low cultivation yields, increasing water temperatures caused by global warming and aging fishing village populations.[29]

Racks type cultivation starts with planting bamboo sticks in the seabed.[29] Nets, to which the laver seeds can stick, are tied to the bamboo posts.[29] Several nets may be connected together.[29] Seeds are planted on the nets in September, often helped by the process of installing nets in multiple layers to facilitate the clinging of the seeds to the net; the layers of nets are separated and re-installed once the seeds are well attached.[29] The nets are subsequently moved to a farming area.[29] The rack type nets installed at gim farms are submerged during high tide and exposed to the sun at low tide; this limited exposure to the sun allows for a certain amount of photosynthesis that's helps maintain the original flavor of the gim.[29] Farming gim using the rack technique is an eco-friendly cultivation method.[29]

Gim cultivation with floating rafts is the most suitable for mass-production because it is less labor-intensive than rack cultivation. This method keeps the laver submerged in the water during both the high and low tides.