The Naitonal Institute of Fisheries Science (NIFS) conducted a sighting survey to find whales inhabitating in East Sea from April 16 to May 9 (for 24 days), and it found 8 species and 39 populations of marine mammals (total 2,298 individuals).

The Cetacean Research Insitute under the NIFS has annually conducted the cetacean resouces survey since 1999, and the sighting survey team for the ceatacea resource in East Sea observed a variety of rare whales including false killer whale (Pseudorca crassidens), sperm whale (Physeter macrocephalus),  killer whale or orca (Orcinus orca), and etc.

Large whales have been frequently observed on the East Sea and South Sea, but this is the first time that a large number of rare whales of various species have been observed, which can be seen as a positive sign of increasing species diversity in the Est Sea.