A South Korean fishing company has successfully farmed salmon at a seawater cage off the east coast for the first time in the country, paving the way for the mass-production of the fish, officials at the Gangwon provincial government said Wednesday.

The salmon farmer, Donghae STF, which made a shipment of salmon farmed at the cage off the coastal town of Goseong on the country's east coast this week, plans to supply 400 tons of farmed salmon to outlets of the country's major discount store chains and raw fish restaurants by the end of the year.

Supported by the government and South Korea's northeast province of Gangwon, Donghae has farmed salmon at the facilities capable of producing about 2,000 tons of salmon since 2013.

The salmon farming started at freshwater fish farms in PyeongChang and Yeongwol in the same province, where salmon eggs were hatched into fry before being grown as 200- to 400-gram young salmon and then the farmed salmon were transported to the sea cage.

The farmed salmon, which the company will ship out, have reached a harvestable size of 4 to 5 kilograms since they were transported to the cage in November last year.

Donghae made shipments of sample farmed salmon on a pilot basis to hotels in Seoul and its nearby regions last year, which received positive consumer response.

Salmon, a cold-water fish, can be farmed at the sea's surface from October to May. But the fish could die in the summer time when the water temperature rises above 20 C, making it difficult for the fish to be farmed in all four seasons.

In the seas around the cage off Goseong, cold currents flow all year around and waters 10 meters below the surface always maintain a temperature less than 20 C, offering a suitable environment for farming salmon and trout.

Provincial government officials said the production of 10,000 tons of farmed salmon will provide the province with an estimated 264.3 billion won (around US$233 million) in economic benefits, adding the province will be able to replace half of frozen salmon imports, which amount to 32,000 tons annually, with South Korean-made salmon if the target of increasing farmed salmon production to 20,000 tons is achieved by 2020.

Salmon farming has been dominated by a small number of farming regions -- Chile, Norway, Canada and Scotland. (Yonhap)