2,900 jellyfish stings and counting, tourists prickle during Korea's peak beach season

Over 2,900 cases of jellyfish stings have been reported at popular beaches this summer alone, sparking nationwide safety concerns during the peak tourism season.

Numerous jellyfish inside a fishing boat near Songjeong Beach in Haeundae, Busan, on Aug. 1. [YONHAP]

Over 2,900 cases of jellyfish stings have been reported at popular beaches this summer alone, sparking nationwide safety concerns during the peak tourism season.

On July 20, a group of tourists suffered jellyfish stings on their hands and feet while surfing at a beach in Yangyang County, Gangwon, around 4 p.m. Three women, two in their 20s and one in her teens, received immediate treatment from emergency responders and were able to return home.

According to the Ministry of Oceans and Fisheries, approximately 2,900 jellyfish stings have been recorded nationwide this summer as of Sunday, though the actual number is likely higher due to underreporting.

Jellyfish swims near Gyeongpo Beach in Gangneung, Gangwon, on July 22. [YONHAP]

Beaches in Busan are seeing the highest number of incidents. The Busan Metropolitan Government said on Tuesday that as of Monday, 947 jellyfish stings occurred at six of the city's seven beaches, excluding Dadaepo. Haeundae Beach reported the highest number of stings with 328 cases, followed by Songjeong Beach with 217, Songdo Beach with 144, Gwangalli Beach with 120, Ilgwang Beach with 98 and Imnang Beach with 40.

"I was stung by a jellyfish while swimming and the pain lasted for a while, leaving my legs red and swollen," said 38-year-old Lee, who was stung at a beach in Busan in late July. Lee also called for measures to address jellyfish at beaches where millions of people visit in summer.

The rise in jellyfish stings is not limited to Busan. Jeju Island reported 346 cases across its 12 beaches as of Sunday, a nearly fourfold increase from last year's 92 cases. Jeju City alone saw 269 stings across eight beaches, while Seogwipo reported 77 cases across four beaches.

Gangwon also saw a dramatic rise in cases, with 554 reported this year compared to just 45 last year. In Gangneung alone, there were 240 cases, with Gyeongpo Beach hit the hardest with 114 stings. Other areas in the province, including Yangyang and Sokcho, also reported sting cases.

Two types of jellyfish can be commonly found at Korean beaches: the Aurelia aurita, or moon jellyfish, and Nomura's jellyfish. Moon jellyfish, found in Korea's Saemangeum estuarine tidal flat, measure about 20 to 30 centimeters and are relatively less toxic. In contrast, Nomura's jellyfish can grow up to two meters long and are highly poisonous.

Nomura's jellyfish originate from the lower reaches of the Yangtze River in China and are carried by currents to Jeju Island and the South Sea, West Sea and East Sea. Stings from Nomura's jellyfish can cause swelling, fever, muscle paralysis, difficulty breathing and shock.

The number of Nomura's jellyfish observed along the coasts of Jeju and the South Sea surged from 0.3 per hectare (10,000 square meters) last year to 108 per hectare as of July, according to the National Institute of Fisheries Science (NIFS). This equates to roughly one jellyfish per 10 square meters, marking the highest number recorded since monitoring began in 2015.

The Ministry of Oceans and Fisheries issued a moon jellyfish advisory for Jeolla and South Gyeongsang on May 27 and South Chungcheong on June 24.

The Nomura's jellyfish advisory was first issued for Jeju Island on July 5 and later extended to South Gyeongsang, Busan, Ulsan and the coasts of North Gyeongsang on July 12, with the latest advisories for South Jeolla and Gangwon on July 23.

A moon jellyfish advisory is issued when more than five jellyfish are found within 100 square meters, while a Nomura's jellyfish advisory is issued when one or more of these jellyfish is found within 100 square meters and private and public monitoring exceeds 20 percent, indicating potential risks to fisheries.

Jellyfish float near Songjeong Beach in Haeundae, Busan, on Aug. 1. [YONHAP]

Experts suggest several factors for the sudden jellyfish surge. While global warming may play an indirect role, they point to an increase in artificial structures that provide surfaces for jellyfish larvae to attach and breed, along with environmental changes such as eutrophication that create favorable conditions for jellyfish to thrive, as a more direct cause.

"Although a more exact reason needs to be found, given that jellyfish are born between February and April, it's more likely that an increase in man-made structures is the primary factor rather than global warming," said Kim Kyung-yeon, a marine and fisheries researcher at NIFS.

Kim expects the jellyfish numbers to decrease in September and disappear around November.

If you are stung by a jellyfish, the NIFS advises you to exit the water immediately and rinse the affected area with beach water or a saline solution. If pain persists, applying a hot pack may help alleviate discomfort. Seek emergency medical attention right away if severe symptoms occur.

BY WEE SUNG-WOOK, CHOI CHUNG-IL, WOO JI-WON [woo.jiwon@joongang.co.kr]