Farmed halibut from Gijang-gun, Busan, were found to contain excessive levels of mercury, Tuesday.

According to the Ministry of Oceans and Fisheries, three farms in the region were found to have shipped off halibut with mercury levels surpassing acceptable standards. Nearly 4 metric tons of fish from these fish farms were distributed to shops in Busan, Pohang, Ulsan and other destinations on June 29.

All remaining fish at the farms have been culled, and the shipped fish were ordered to be recalled. 

The Ministry of Fisheries had been running inspections at fish farms nationwide when it encountered mercury levels of between 0.6 and 0.8 milligrams per kilogram in the fish from the farms, exceeding the permissible level set at 0.5 mg per kilogram.

Halibut is popularly used for sashimi in Korea. The unprecedented crisis sent a wave of shock through consumers. Fearing the news would hamper the fisheries industry, the Ministry added the explanation that Busan’s output of halibut accounts for only 0.5 percent of the total farmed halibut in the country.

Since 2013 and in over 500 inspections run by the Ministry of Fisheries for harmful metal substances in fishes, this is the first time that excessive levels of mercury have been detected in farmed halibut. The farms in question were last inspected in May, when nothing was found to be out of the ordinary, according to the ministry.

Authorities are currently running tests on the fish feed used at the farms. Experts speaking to the media speculated that contaminated ground fish fed to the halibut could have caused an accumulation of mercury in full-grown halibut on the upper tier of the food chain.

By Lim Jeong-yeo (kaylalim@heralcorp.com)