New Zealand Forest and Bird is urging diners to boycott a popular Chinese delicacy amid concerns over inhumane fishing practices.

Shark-fin soup is a symbol of wealth and prestige in Chinese culture, selling for as much as $300 a serve in some local restaurants.

But Forest and Bird advocacy manager Kevin Hackwell said targeting sharks for their fins was a "barbaric practice".

Sharks in New Zealand waters can be finned as long as they are dead, but Mr Hackwell said there was plenty of evidence that live finning took place.

"We know it's going on. We've been asking the Government for quite a while to do something."

While the Government was set to review shark fishing regulations in 2013, the public could do something now by avoiding restaurants that had shark fin on the menu.

"People have power as consumers. We're the ones who buy the products," said Mr Hackwell.

Shark-finning is illegal in many countries including Britain, the United States and Australia.

The fins are the most valuable part of the animal. After they're removed, the shark is often thrown overboard.

Aucklander James Lawson saw a group walk out of the popular Grand Harbour Restaurant after a confrontation over the presence of shark fin on the menu. Attempts to get comment from the Viaduct eatery yesterday were unsuccessful.

"Finning is prohibited in Australia, the USA, the EU, but not here," said Mr Lawson. "This is abhorrent. Is this what we do in New Zealand?"

Another Auckland restaurant that sells the soup is Crystal Harbour. Its manager, Carlton Sui, said complaints were uncommon.

"I think it's just a real minority of people," said Mr Sui.

Shark populations are rapidly declining worldwide on the back of the $1 billion fin industry and as a "by-catch" of targeting other fish.

A Department of Conservation source said New Zealand tuna fishermen caught up to two and a half times as many sharks as tuna.

Greenpeace marine biologist Karli Thomas said: "A lot of these sharks are being taken in fisheries targeting tuna, but the value of the shark fins means they're a kind of target in themselves."