HONG KONG » Shark fin traders in Hong Kong have laid out thousands of fins on rooftops in what appears to be a move to escape public scrutiny of their industry.

Thousands of the freshly cut fins were seen blanketing the roof of an industrial building in Hong Kong this week.

Environmental campaigner Gary Stokes, who took the first photos of the drying on Jan. 1, said today that the traders usually dried their fins on the sidewalks. He suspected that the traders went upstairs to avoid pressure from concerned passers-by.

Hong Kong is the world center of the shark fin industry, accounting for about half of global trade. Environmental campaigners, citing government statistics, say more than 10,200 metric tons of shark fin were imported into Hong Kong in 2011.

Shark fins are popular in Asia where delicacies such shark’s fin soup, which is mostly tasteless, are served at special occasions such as wedding banquets. However, environmentalists say overfishing is threatening shark species.

Shark fins were banned in Hawaii in July 2010.

Stokes said a video he released in March showing thousands of dried shark fins laid out on the side of road drew attention to the practice. He added that he had heard the tourism board "was not too wild about it" because tourists had complained after coming across drying fins.

But Ho Siu-chai, president of the Hong Kong Sharks Fin Trade Merchants Association, denied there was pressure, saying the traders were using the roof because they probably didn’t have enough space and wanted to take advantage of the cool, clear weather.

Stokes said many of the shark fins coming into Hong Kong were being shipped to mainland China.

"With the middle class becoming more affluent, the demand is definitely growing" in mainland China, Stokes said. "But in Hong Kong it’s actually decreasing. I think that in Hong Kong people are starting to realize that it’s not that cool."

The growing environmental concerns have prompted some five-star hotels in Hong Kong to stop offering shark’s fin soup at banquets and the city’s biggest airline, Cathay Pacific Airways, to stop carrying it in air cargo.

The Chinese government also said last year it was banning shark’s fin soup from official banquets in an attempt to curb corruption.

Some 75 million sharks are killed for their fins only each year, according to the European Union. The sharks are typically thrown back into the sea to die after their fans are harvested, a practice that the EU banned last year. Fins can sell for as much as $700 a pound.

Shark fin trading is not regulated in Hong Kong except for three species that require permits from the countries from which they were exported.