Hong Kong, Jan 6 - Wildlife campaigners in Hong Kong were fighting Wednesday to stop a rare bluefin tuna bought for $175,000 from being served in a Japanese restaurant chain in the city.

The 232-kg, 15-year-old fish was bought at an auction in Tokyo by the Hong Kong restaurant chain Itamae Sushi and a Japanese partner chain Kyubei Sushi.

The price it fetched at Tuesday's auction was the highest paid in nine years in Japan for a giant tuna, but conservationists said fishing of the bluefin species should be halted as stocks dwindle.

A mock memorial notice taken out by the World Wide Fund for Nature (WWF) in Hong Kong newspapers Wednesday mourned the fish's death and appealed to people to avoid eating the tuna.

The notice said a number of bluefin tuna species are "critically endangered and on the road to extinction" and calls consumption of the species "unsustainable and irresponsible".

"An obituary commemorating the commercial extinction of various species of bluefin tuna will be needed very soon if the current fishing frenzy continues," it warned.

Both northern and southern bluefin tuna are listed as critically endangered while Pacific bluefin tuna is considered vulnerable.

The WWF, which said it hopes to see a ban on trade in bluefin tuna introduced this year, began handing out leaflets Tuesday evening to diners outside branches of the sushi chain.

However, Itamae Sushi owner Ricky Cheng Wai-to told Wednesday's South China Morning Post that another restaurant chain would have bought the fish if Itamae Sushi had not.

"We would have stayed away from the auction if the Hong Kong or Japanese government made importing the fish illegal, but this is not the case," he told the newspaper.

Japan accounts for 80 percent of the world's bluefin tuna consumption.  (dpa)