Japan will reject a recent decision by member countries of the Washington Convention to regulate international trade in sharks whose populations have declined sharply due to over-hunting for their fins, government sources said Friday.

The government will file a reservation about the regulation, arguing that sharks should be managed under existing fishery management systems, the sources said. The move could come under international fire as another sign that Japan, known for its heavy seafood consumption, is indifferent toward global efforts to preserve endangered marine resources, experts said.

Signatories to the 1973 pact, officially called the Convention on International Trade in Endangered Species of Wild Fauna and Flora, or CITES, decided in March at a conference in Bangkok to require exporting countries to issue certificates of permission for international trade in sharks. The decision drew support from more than two-thirds of the voters.

Japan's reservation, to be filed with the CITES secretariat, will cover three species of hammerhead shark plus oceanic whitetip and porbeagle sharks, the sources said, adding that Japan will accept another decision to regulate trade in manta rays.

Fisheries Agency data show that annual hauls of oceanic whitetip sharks in Japan stood at about 40 tons in 2011, some of which appeared to be exported for their fins.

Japan has already rejected CITES decisions to ban trade in seven species of whales, including sperm and minke whales, and regulate trade in basking sharks, whale sharks, great white sharks and sea horses.