The dugong, which has been designated a “National Monument” by Japan, lives in the ocean surrounding Okinawa prefecture. It is a large water mammal that is in the Sirenia order with the manatee. The main island of Okinawa is at the northern end of the dugong’s habitat range. The Japanese Ministry of the Environment considered the dugong as being at extreme risk of extinction and placed it in the “Endangered Species IA Class”. Global interest in the dugong’s survival is very high as shown by three resolutions adopted by the International Union for Conservation of Nature (IUCN) for the protection of the Okinawan dugong.

In 2001, the Japanese Ministry of the Environment announced that a three-year survey confirmed a total of 12 Okinawan dugongs. At the time of revisions to the Red List (of Japanese endangered species) in 2007, it was estimated that 50 or fewer Okinawan dugongs were alive. Experts, however, have pointed out that the “possible population [for Okinawan dugongs] is ten or fewer”.

Dugongs have frequently been sighted at Henoko, the land area chosen to be the site for relocation of Futenma Air Station. An environmental impact assessment conducted by the Japanese Ministry of Defense for the proposed station relocation confirmed the presence of three dugongs. The Ministry claims it will “be able to preserve [the dugong] through environment protection measures” even after going ahead with the landfill project for the station.

However, dugongs clearly feed in the ocean off Henoko and in adjacent Oura Bay. Japanese environmental groups are strongly opposed to the offshore landfill project at Henoko because it will decimate sea grass beds which substance for dugongs. Also the sea routes for transporting landfill material will encroach on their migratory path.

Environmental groups in both the U.S. and Japan brought the “Okinawan Dugong” case to the U.S. Federal Court in San Francisco under the National Historical Preservation Act (NHPA) in 2008. The court ruled that the dugong must be protected by the NHPA and that the base construction clearly violated that law. It also ordered the Department of Defense, as a responsible party, to address the protection of dugongs.

From another perspective, it appears the Okinawans are the dugongs of Japan and need immediate help to survive.

ジュゴンも守って!

 沖縄近海には国の天然記念物ジュゴンが生息している。マナティと同じ海牛目の海生哺乳動物で、沖縄本島が生息域の北限とされる。環境省は絶滅の危険性が極めて高い「絶滅危惧種IA類」に指定。国際自然保護連合(IUCN)が沖縄のジュゴン保護を求める勧告・決議を3度採択するなど国際的に関心が高い。

 環境省は2001年から3年間の調査で、延べ12頭を確認したと発表。07年のレッドリスト改訂の際には、成体の個体数を50頭未満と推定した。専門家の間では「生息可能性は10頭以下」と指摘されている。

 米軍普天間飛行場の移設先とされる名護市辺野古の周辺でも、たびたびジュゴンが目撃されている。移設に伴う防衛省の環境影響評価では3頭を確認。埋め立てを実施した場合でも、「環境保全措置で保全できる」としている。

 一方で、辺野古沿岸や隣接する大浦湾ではジュゴンが餌を食べた跡が多数見つかっている。日本の環境団体などは埋め立てで、ジュゴンの餌となる海草藻場が減少することや土砂を運ぶ船のルートがジュゴンの回遊経路と重なることなどから、ジュゴンの生息に大きな影響が出ると埋め立てに反対している。

 日米の環境保護団体などが米国国家歴史保存法(NHPA)に基づき、米国で起こした「沖縄ジュゴン訴訟」でサンフランシスコ連邦地裁は2008年、「ジュゴンは同法で保護されるべきで、基地建設は同法違反」と判断。米国防総省に対し、当事者としてジュゴン保護に取り組むよう命じた。

 見方を変えれば、沖縄が“日本のジュゴン”のようであり、緊急の保護を必要としている。(福元大輔)