Hong Kong authorities have seized more than a tonne of shark fins as activists warn traders are sneaking the sought-after delicacy into the city by mislabelling shipments to get around bans by major transporters. 

The city is one of the world's biggest markets for shark fin -- often served as a soup at expensive Chinese banquets -- but it prohibits the trade in products taken from endangered species. 

Companies including airlines Cathay Pacific and Virgin and shipping company Maersk have barred the transportation of shark fins following public outcry over the trade, which is blamed for the deaths of tens of millions of sharks every year.

Yet in the first two months of 2017 more than a tonne of fins from endangered hammerhead sharks and oceanic whitetip sharks were seized by Hong Kong customs.

Four containers of shark fin weighing 1.3 tonnes were discovered on separate occasions at Hong Kong's main sea port and were from India, Egypt, Kenya and Peru, the government said Monday.

Anyone found trading in products from endangered species could face a fine of HK$5 million ($643,952) and two years in jail.

The city's government in 2013 said it would stop serving shark fin at official functions, while luxury hotel chains Shangri-La and Peninsula Hotels also took it off their menus in 2012 and 2011.

But the culture of consuming shark fin remains widespread and it is found on menus in seafood restaurants across the city.

The new seizure coincided with the publication of a report by international conservation group Sea Shepherd which said large shipments of fins were still arriving in Hong Kong, despite carrier bans.

Traders are sneaking in the product by giving them false labels, the report said. 

Shipments on Virgin Airlines Cargo and Cathay Pacific have been declared as "fish products", while other shark fin consignments have been marked as "seafood", "dried marine products" and "dried goods", it added.

Cathay banned shark fin shipments on all its flights in 2016, Virgin in 2011.  

"As with most environment issues, the first challenge is to change the rules. But the second and much harder challenge is to enforce those rules," Sea Shepherd said.

Its investigation found large shipments still arriving in the city in recent months, including two 45-foot (13.7 metres) containers full of fins from the Middle East.

Sea Shepherd is now helping carriers review their systems to ensure the bans are enforced.

Virgin Group founder Richard Branson congratulated the Sea Shepherd team for exposing what he called a "foul" trade.

"Thousands and thousands of sharks slaughtered just for their fins to be turned into bowls of soup. For those people who have knowingly participated they need to hang their heads in shame," he was cited as saying in Sea Shepherd's statement.

Source: AFP