Dugongs are marine mammals that are closely related to manatees. 

Dugongs are marine mammals that are closely related to manatees.  (Pixabay)

CAMP FOSTER, Okinawa — The Japanese government is ending its search for the dugong, an endangered cousin of the manatee, in waters off Okinawa where a controversial Marine Corps runway is under construction.

A committee of the Okinawa Defense Bureau decided May 21 that the long absence of the dugong from Oura Bay, where the government is building the runway from reclaimed land, means it is not likely to return, according to the meeting materials released on the bureau’s website.

Fewer than 10 dugongs were left in the waters around Okinawa, according to a December 2019 report by The Japan Times.

Cries that experts attributed to dugongs were recorded in 2020, and Okinawa prefecture asked the bureau to expand its search in 2022 following the detection of dugong DNA in excrement, the materials said.

Starting in April 2020, the bureau added an expanded helicopter search, an additional surveillance ship and five additional underwater audio recording devices in Oura Bay. It also examined signs of seaweed feeding in the bay and set up three underwater cameras in the same area, according to the materials.

After years of searching without success, the bureau concluded the dugongs “do not have a permanent residence in that area,” and that additional measures are not required to mitigate or reduce “the effects of construction vessels and the associated underwater noise on the dugong habitat,” according to the document.

The dugong became not just an environmental concern but part of the rationale behind opposition to the Marine Corps runway under construction at Camp Schwab. The new airfield is meant to replace Marine Corps Air Station Futenma farther south on Okinawa.

Runway work resumed in January after the prefectural government lost a series of legal challenges to project design changes and construction permits.

Under Gov. Denny Tamaki, a firm opponent of the island’s U.S. military presence, the prefecture also argued for halting the project on environmental grounds, citing a soft sea bottom, and the prospective harm to endangered coral reefs.

The prefecture’s legal fight kept Japanese courts busy but even the U.S. judicial system weighed in.

The 9th Circuit Court of Appeals turned back a challenge from U.S. environmentalists to the Defense Department’s plans for the runway in May 2020. The lawsuit, filed in 2003 by the Center for Biological Diversity, U.S. and Japanese environmental groups and individuals, argued the Pentagon planned the airfield project without considering potential adverse effects on the dugong.

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Keishi Koja is an Okinawa-based reporter/translator who joined Stars and Stripes in August 2022. He studied International Communication at the University of Okinawa and previously worked in education.

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