Unusual Increase in Water Temperature in the East Sea: Tropical Fish from Southeast Asia Appear

This summer, the water temperature in the coastal and inshore waters of the East Sea has risen by more than 3 degrees above the average of the past 30 years.

In the East Sea, where the water temperature has risen, not only fish that live in the waters of Jeju Island appear, but also tropical fish that live in the waters of Southeast Asia.

Reporter’s Coverage

Reporter Lee Jun-ho covered the scene at Sacheon Beach, Gangneung-si, Gangwon-do.

The surface temperature of the sea water here is about 26 degrees, and upon inspection, a variety of fish species were found.

Subtropical Fish Species Found

Around the rocks at a depth of 5 meters, a fish with bright black stripes on a bright yellow background was spotted. This is the “panbream”, a subtropical fish species that lives from Jeju Island and the southern seas of Japan to the tropical regions.

As I went deeper, I saw a tropical fish called a “Blue Bream” swimming by, which appeared to have a blue fluorescent substance all over its body.

Also notable is the “sunfish”, which can be seen in the southern seas and has spines as large as its body that protrude high on its back.

Jeju Island’s Signature Fish Found in Gangwon-do

Jeju Island’s signature fish, the sea bream, gathers in groups of hundreds in the waters off Gangwon-do, as if trying to show off its power.

According to Kim Man-jin, a researcher at the East Sea Fisheries Research Institute, “The sea bream has been confirmed to live as far as the coasts of Ulleungdo and Dokdo, but the high temperatures this summer show that the marine ecosystem off the coast of Gangwon-do is changing.”

Causes of the Increase in Water Temperature

The surface water temperature of the East Sea has risen by 1.8 degrees in half a century, and this summer the increase is even greater.

It is believed that the warm atmosphere adjacent to the sea had an effect.

According to Jung Hae-geun, a researcher at the East Sea Fisheries Research Institute, “In August 2024, the surface water temperature in the coastal waters of the Eastern Sea increased by 1.6°C compared to last year and by 3.3°C compared to the 30-year average.”

In addition, the inflow of the high-temperature Tsushima warm current passing through the Korea Strait from southern Japan into the East Sea has continued to increase since the 1990s, so the occurrence frequency of tropical and subtropical fish is expected to further increase.

This is Junho Lee from MBC News.

Underwater photography: Yonghan Yoon, Junho Lee