TOKYO

The International Union for Conservation of Nature has updated its Red List of Threatened Species, designating the dugong in waters off the southernmost Japan prefecture of Okinawa in the "critically endangered" category.

The organization warned that the number of dugongs off Okinawa has fallen to 10 or less and is in decline. The "critically endangered" category is the highest among the IUCN's five categories reflecting the degree of extinction risk.

The IUCN also cited the threat to the marine mammal posed by construction work related to the relocation of the U.S. Marine Corps' Futenma air base to the Henoko coastal area in Nago in Okinawa from its current site in Ginowan in the island prefecture.

"The loss and damage to these seagrass beds (near the construction site) is likely to be a serious impediment to the recovery of the dugong population in Okinawa," it said. The construction project involves landfill work off Henoko.

Investigations by the Japanese Defense Ministry's Okinawa Defense Bureau had previously confirmed three dugongs near the main island of Okinawa. However, one of them was found dead in March this year, while the other two have not been seen since September 2018.

The dugong is also designated as a critically endangered species in the Japanese Environment Ministry's Red List.

Jiji Press