Dugongs, an endangered marine species, in 2012 were inhabiting the reclamation site in Okinawa chosen for the relocation of the U.S. Futenma base, the first time their presence has been confirmed there in three years, a survey by the Okinawa Defense Bureau revealed Saturday.

Only a small number of dugongs live in waters near the Japanese archipelago. But a survey report obtained by Kyodo News through a freedom of information request confirmed seaweed had been eaten by dugongs at the planned reclamation site between April and June last year.

Similar traces of seaweed eaten by the mammals were found near the area in June 2009, but no further evidence indicated that they had since inhabited the site.

The bureau submitted an application for the reclamation work to the Okinawa Prefectural Government in March, saying there would be little impact on the environment, but it chose not to disclose the survey results.

The finding could affect Gov. Hirokazu Nakaima's decision on whether to approve the requested reclamation site off the coast of the Henoko district in Nago, on Okinawa Island.

The waters off Henoko are known for abundant seaweed that dugongs eat. The bureau's survey suggests the mammals have repeatedly visited the area as a feeding site.

Tokyo and Washington have agreed to relocate U.S. Marine Corps Air Station Futenma from the crowded city of Ginowan to the coastal area of Nago as part of the realignment of American forces in Japan. But the plan has been stalled for years by vehement opposition in Okinawa, which hosts the bulk of U.S. military bases in the nation.

A bureau official said the survey findings do not affect its environmental assessment of the reclamation project and that it does not intend to review the relocation plan.