The shark fin trade between Hong Kong and China decreased nearly 90 percent in 2013, animal rights group World Wide Fund for Nature (WWF) has revealed.

Shark fin exports to mainland China fell from 1.2 million kilograms in 2012 to 113,973 kilograms the following year. Vietnam has now overtaken China as Hong Kong's biggest re-export market, with mainland China dropping to fourth.

The decrease comes as a result of China President Xi Jinping's crackdown on exuberance among the Chinese elite and the action of environmental groups to prevent the killing of sharks for their fins.

"We were very surprised when we saw this figure as the mainland has traditionally been Hong Kong's biggest re-export market," WWF-Hong Kong senior programme director Tracy Tsang Chui-chi told the South China Morning Post.

"We do not rule out the possibility that the central government's anti-corruption measures could have played a role in the big drop in re-exports," she added.

It is thought that Xi's crusade against extravagance has been instigated by public outbursts against luxurious banquets on Weibo, the Chinese equivalent of Twitter.

Anger is well-founded with luxury dishes like shark fin soup and sea cucumber reaching up to £170 in price, more than a worker's weekly wage in China.

It is estimated that £21 billion worth of food is wasted every year in China and Xi has pledged an "empty plate action" in his war on corruption and disapproval of waste.