The city is one of the world's largest markets for shark fin, which is viewed by many Chinese communities as a delicacy and often served as a soup at expensive banquets.

While domestic consumption has shrunk after years of activist campaigning, Hong Kong remains a vital trade hub for shark fins -- both legal and illegal -- headed for the Chinese mainland and Southeast Asia.

"Last year, over 90 percent of shark fin imports in Hong Kong were re-exported, and a major market is mainland China," said Loby Hau, oceans sustainability assistant manager at WWF-Hong Kong.

The city regulates its shark fin trade using an international treaty on endangered species, meaning certain types of fins must have export permits showing they were sustainably captured.

The latest meeting of the 184-nation Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which began in Panama on Monday, may add protections for two major shark families.

Researchers say the proposals, if passed, will protect a huge number of shark species and place further pressure on Hong Kong's law enforcement, which is already battling a surge in illicit shark fins.

Hong Kong seized 27.5 tonnes of legally regulated shark fins in 2021 and 29.5 tonnes the year before, a government spokesman told AFP. In 2019, the figure was just 6.5 tonnes.

Marine biologists estimate that upwards of 100 million sharks are killed each year, pushing vital apex predators towards extinction and ocean ecosystems to the brink of collapse.

The fins are usually sliced from their bodies and the animals thrown back into the sea where they suffer a slow death.

There are signs Hong Kong consumers have become more aware.

A survey in 2009 found that 73 percent of respondents had eaten shark fin in the preceding year, but a decade later that number fell to 33 percent.

The government, major caterers and image-conscious brands have also been keen to bolster their environmentalist credentials by ditching shark fin from banquet menus.

But in Hong Kong's "Dried Seafood Street", where shops display shark fins behind glass like trophies, business remains steady.

"Fewer people want to buy shark fins nowadays, but we have our regulars, mostly the elderly," said one shopkeeper who declined to be named, adding that her customers spend an average of HK$2,500 ($320) per catty (a measurement equal to 605 grams).

A nearby restaurant was offering a range of shark fin soups that maxed out at HK$980 per bowl.

It is hard to tell the level of compliance among import-export firms and retail vendors, according to Stan Shea, marine program director for the BLOOM Association Hong Kong.

"As an ordinary citizen, the only thing you can do is ask the shopkeeper, 'Are your fins legal?'" he told AFP. "(Sellers) are not required to label their goods and very few do."

Once a piece of shark fin is skinned and processed, the only reliable way to check if it belonged to an endangered species is DNA analysis -- which Shea and other researchers conducted in 2014.

More than 10 percent came from sharks regulated by CITES at the time.

A more recent 2020-2021 study by Shark Guardian in Taiwan found half of shark fin traders were selling protected species.

Blue sharks -- which industry representatives argue have stable populations -- are the most commonly found among fin traders.

But that could change if a CITES proposal backed by more than 40 countries to regulate all species of requiem sharks is successful.

"If the proposal is passed, and assuming the market composition hasn't changed since 2014, then 90 percent of shark fins on the market will need to have export permits," Shea said.

Over the past five years, Hong Kong has prosecuted five people for importing endangered shark fin without a license -- an offense punishable by up to 10 years in jail and a HK$10 million fine.

The government last year expanded the law on organized crime to cover wildlife smuggling, but no such prosecutions have taken place.

Hau, of WWF-Hong Kong, called on authorities to conduct more inspections and impose mandatory record-keeping for shark fin vendors.

"If this Panama conference adds more species to (CITES regulations), the government should pay close attention," he told AFP.

"Wildlife smuggling has become very systematic and organized, so investigations need to be dialed up."