Foot-long parasitic ribbon worms infest Han River during eel fishing season

Social Affairs

Published: 28 Mar. 2024, 12:53 Updated: 28 Mar. 2024, 16:31

Foot-long parasitic ribbon worms infest Han River during eel fishing season

Ribbon worms found in the Han River in 2022. [JOONGANG PHOTO]

A significant number of ribbon worms are appearing in the Han River with the arrival of spring.

Ribbon worms, or Lineus alborostratus, are aquatic vermin with a body length between 20 and 30 centimeters (8 to 12 inches). Their presence in the Han River was first reported in 2013.

The worms' arrival overlaps with the glass eel fishing season. The worms prey on the eels — a valuable economic and livelihood source for dozens of fishers.

“The prime fishing season arrived on March 21. However, the eels were killed because of the worms stuck together in a fishing net,” Kim Hong-seok, a 66-year-old fisher, told the JoongAng Ilbo.

“Around 5 kilograms (11 pounds) of worms are entangled with hundreds of eels caught in the net. Slime coming out from the worms kills the eel."

“This year, the worms appeared earlier than the previous year, and the amount also increased. Given this situation, I can no longer continue glass eel fishing and decided to halt it starting Wednesday.”

Dead glass eel and ribbon worms are caught together and placed in a red bucket on Tuesday. [JOONGANG PHOTO]

According to the fishing community in the region, all fishers temporarily decided to discontinue their fishing activities as more than 95 percent of caught glass eels died because of the ribbon worms.

“The fishers’ hands are tied, and our concerns are getting deeper because nothing can be done when glass eels — accounting for more than half of annual income — are present but not catchable,” said Park Chan-soo, 65, head of the local fishing community.

The fishers attributed the status quo to the release of wastewater from the city-run water recycling centers in Gangseo District, western Seoul and Goyang, Gyeonggi.

“The outsourced research team from the city of Goyang cited that the reason [for ribbon worms’ appearances] is a high level of salinity, which is hardly understandable [from the perspective of fishers],” the fishing community told the JoongAng Ilbo. “There has not been any solution.”

They called for precise research and remedies as the river is managed by public authorities.

They cast doubt over the research result, saying “high salinity” is not enough to explain why the ribbon worms only appear in the Han River, but not in other places across the country.

Glass eels are being caught dead because of slime emitted from the ribbon worms. [JOONGANG ILBO]

“As the ribbon worms are found particularly in areas near Haengju Bridge where contaminated water’s flow is blocked by Singok underwater barrage,” said Shim Hwa-sik, a 69-year-old fisher from the community, adding that “correlation between the released water and the parasitic species can be presumed.”

The community also demanded the relocation of the barrage.

An official from the Seoul Metropolitan Government debunked the claim from the fishers’ community.

“The released water is clean and thoroughly managed, maintaining the level of biochemical oxygen demand below 10 ppm,” an official said, stating that the barrage would not be moved elsewhere.

BY JEON ICK-JIN, HAN EUN-HWA [lee.soojung1@joongang.co.kr]