First record of plastic debris ingestion by a fin whale (Balaenoptera physalus) in the sea off East Asia.

Marine pollution caused by plastic litter can threaten the survival and health of marine organisms. In 2019, a juvenile fin whale (Balaenoptera physalus, length: 13.02 m, weight 12,000 kg) was found dead floating on the sea near Jeju Island, Republic of Korea. During the dissection, 45 plastic particles were found in the body of the whale, including fishing lines, plastic filaments, pieces of fishing nets, and Styrofoam particles. The largest item found was a piece of fishing line (1180 mm in length and 1.15 mm in thickness). Filaments, both bundled and separated, were more frequent. Some of the filaments found were entangled with the baleen plate bristles. These observations suggest that plastic pollution is a potential risk for baleen whale species. This is the first record of plastic ingestion by a vulnerable baleen whale species in the sea off East Asia.