South Korean marine ecosystems shift as subtropical species surge

South Korean coastal waters are undergoing rapid ecological shifts due to rising sea temperatures, leading to a significant increase in subtropical species and potentially dangerous marine life.

Data from the Korea Institute of Ocean Science and Technology reveals that subtropical fish species now account for up to 81.8% of fish populations in certain areas of Jeju Island. Similar trends are observed in Ulleungdo, where 58.5% of observed fish are tropical or subtropical, and in Busan's Gijang area, where subtropical species rose from 56% in the late 2000s to 71% in 2025.

Beyond fish species, there has been a surge in sightings of large sharks and jellyfish. Large shark appearances on the East Coast increased nearly fourfold between last year and the same period this year. Additionally, jellyfish sting incidents rose significantly, with moon jellyfish populations in Goseong, Gyeongnam, increasing approximately 71-fold over five years. Experts warn that these changes reflect a fundamental shift in the marine ecosystem driven by climate change.