Fishers, beachgoers feel the sting as giant jellyfish threat grows

Social Affairs

Published: 16 Jun. 2024, 16:35

Fishers, beachgoers feel the sting as giant jellyfish threat grows

An image of Nomura’s jellyfish provided by the Ministry of Oceans and Fisheries [MINISTRY OF OCEANS AND FISHERIES]

The earlier-than-expected arrival of jellyfish weighing over 100 kilograms (220 pounds) is making life miserable for fishers along Korea's southern coast.

A fisher living in a seaside community in Busan said it's a struggle “pulling up fishing nets containing Nomura’s jellyfish which are two meters (6.5 feet) in diameter and weigh over 150 kilograms.”

He said the jellyfish often rip the nets and make fishers “spend twice as long sorting the [marketable] fish from the jellyfish.” Jellyfish stings also damage fish flesh and scales, lowering the catch's commercial value.

This summer's first heat wave, which came earlier this year, has warmed the seas and fostered a jellyfish-friendly environment.

The National Institute of Fisheries Science said Tuesday that the first annual jellyfish advisory was issued for the coasts of South Gyeongsang and South Jeolla on May 27 when there were more than five moon jellyfish per one hundred square meters of seawater.

This year’s advisory was issued 10 days earlier than last year's. It was also the earliest advisory ever issued for both provinces. The institute said such advisories used to be issued in late June or early July.

Dozens of jellyfish are caught by a fishing net which was pulled from the waters off Gochang County in North Jeolla last Wednesday. [YONHAP]

“Moon jellyfish often grow in waters near the Korean coastline,” said Yoon Seok-hyun, a researcher from the institute. “They usually stay dormant in the form of tiny polyps attached to underwater rocks or shells and become active in February.”

Moon jellyfish are smaller and lighter than Nomura's jellyfish and often grow to around 15 centimeters (5.9 inches) in diameter on average.

“It appears that the rising ocean temperature induced by climate change has facilitated the growth and proliferation of the jellyfish,” Yoon said, explaining that environmental changes triggered a change in the species’ lifecycle. The species is known to be most easily observable in late summer.

The Conservation and Management of Marine Ecosystems Act defines Nomura’s jellyfish and moon jellyfish as harmful marine organisms.

Nomura’s jellyfish inhabit waters near North Gyeongsang and Gangwon, while moon jellyfish live in waters near North Gyeongsang and South Jeolla.

Nomura’s jellyfish carry poison that can cause pain and skin rashes. In severe cases, stings by Nomura’s jellyfish can result in death. Moon jellyfish have weaker poison.

The institute said that Nomura’s jellyfish move northeasterly from the East China Sea to the East Sea of Korea.

Although the institute monitors the jellyfish's population and movement, their origin in foreign waters makes it difficult for researchers to track them precisely.

In this year’s survey, the institute found that many of the Nomura’s jellyfish are from China. This finding means that Korea could see a higher number of Nomura's jellyfish this summer.

However, no concrete ways exist to block Nomura’s jellyfish from entering Korean waters.

“Humans cannot control oceanic currents that influence the jellyfish's path,” Yoon said.

Although turtles and filefish can eat jellyfish, predators generally do not favor them.

The researcher said even those predators choose to eat different prey when other options are presented. He noted that jellyfish have “no nemesis in the ecosystem.”

Cleaners remove a jellyfish that turned up on the white sand of Ilgwang Beach in Gijang County, Busan, in 2021. [KIM MIN-JU]

Local governments in coastal areas are also concerned about jellyfish appearances ahead of the summer tourism season.

Busan, a southern coastal city, has seen an increase in jellyfish stings in recent years. In 2019, 109 cases were reported in seven beaches in the city. The number surged to 680 in 2020 and 742 in 2022.

Although accidents shrank to 452 last year, beach visitors decreased by 15 percent compared to 2022.

In the summer peak season, first responders or lifeguards on the beach provide on-site treatment to beachgoers stung by jellyfish and catch jellyfish to prevent such accidents.

The city of Busan is preparing measures to prevent jellyfish stings, including the installation of nets to block jellyfish from entering swimming areas at Haeundae Beach, Songjeong Beach and Songdo Beach.

At Dadaepo Beach, a fishing vessel will collect jellyfish. Gijang County will encourage fishers to exchange jellyfish they catch for cash.

An official from the Busan city government pledged to prevent jellyfish damage by utilizing “10 state-owned vessels and seven fishing boats, as well as other equipment such as jellyfish cutting nets and scoop nets” to stop jellyfish from appearing.

BY KIM MIN-JU, LEE SOO-JUNG [lee.soojung1@joongang.co.kr]