Toxin in shellfish is spreading

Shellfish poisoning spreading fast from the southern coast is giving Korean fishermen a headache - and can do even worse to the unwary consumer who eats the poisoned crustaceans.

Lee, 53, who has an oyster farm on the coast of Hansan Island in Tongyeong, South Gyeongsang, expects to lose more than 17 million won ($15,200) of business this month. He has yet to harvest around 10 percent of oysters from his farm, but he expects that a ban on gathering shellfish to soon reach his region.

“What is most frustrating is that consumers incorrectly think that all oysters from the southern coast have excessive amounts of PSP, driving demand down,” said Lee.

Because of the spread of paralytic shellfish poisoning, or PSP, harvesting bans have been put on many coastal areas, starting with Jinhae Bay, in Jinhae, South Gyeongsang on March 29. In less than one month, PSP spread north, crossing over Busan and onto Ulsan in the eastern coast, and then to the western coast. Experts say that this year’s poison levels are the highest ever for some areas, due to excessive rain.

All of those areas had shellfish that contained more than the permitted level of PSP, which is 80 micrograms per 100 grams of shellfish.

When humans digest PSP, it can cause nausea, vomiting, diarrhea, a choking feeling and can even be fatal in extreme cases. Mok Jong-su, a researcher at the National Fisheries Research and Development Institute, said the most common symptoms are “vomiting, which leads to difficulty breathing, and a muscle paralysis.”

Jung, 44, who operates a wholesale business for mussels in Masan, South Gyeongsang, said that in a matter of days, his mussel supply is half what it normally should be and wholesale prices have fallen by 16 percent.

Record amounts of PSP were found in shellfish in Geoje, South Gyeongsang, in April 1996, at an average of 150 times the permitted amount. This year, waters near Gadeok Island, Busan, surpassed this level.

By Lee Key-one [jainnie@joongang.co.kr]