Ecosystem chaos
When a shark's fin is sliced off, the animal dies, said Yvonne Sadovy, lead author of the Marine Policy study and a professor in the School of Biological Sciences at the University of Hong Kong.
"It cannot move, feed or swim, so it just starves to death on the sea bottom. Maybe it is like cutting the wings off a flying plane: The plane will be destroyed," she said.
Sharks need their fins for steering, balancing and, for some, breathing.
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A replacement for Shark Fin Soup from Four Seasons, Double Boiled Maitake Mushroom soup.
"There are sharks that must continue swimming to be able to breathe, as they rely on the forward motion to keep water passing through their gill slits and get oxygen," said Stan Shea, marine program director for the Bloom Association Hong Kong, a nonprofit that works to preserve the marine environment.
When their fins are cut off, "they are likely to die of suffocation, as they are no longer able to breathe by swimming forwards. (For others), they are unlikely to suffocate but die either by starvation or watching as other animals 'consume' them alive."
In addition, as a predator at the top of the food chain, sharksa are critical to maintaining balance in the ecosystem, Shea said. Its loss could cause "behavioral change" and "chaos."
For example, when numbers of sharks decrease, their prey will increase and overeat the next level on the food chain, which is why cownose rays wiped out the scallop population in North Carolina, Sadovy said.
"Most sharks are important predators and therefore can play key roles in keeping ecosystems functioning. Depletion of sharks is expected to have negative effects on populations of prey species, many of which may be also be sharks, or rays," said Nick Dulvy, co-chairman of the International Union for the Conservation of Nature's Shark Specialist Group.
'Why the heck would you eat it?'
Eating shark meat could be harmful to humans, too.
Studies have found that sharks accumulate marine toxins, as long-lived predators at the top of the food chain. The levels of these toxins, including mercury, lead and arsenic, exceed recommended dietary levels, according to articles in Marine Pollution Bulletin.
Hong Kong's Centre for Food Safety warned against the consumption of predatory fish species after finding a sample from a supermarket that contained a level of mercury eight times the permissible limit in 2017.
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Shark fin is easily accessible in Hong Kong at the Dried Food Market.
"The main food safety concern for shark fin/meat and other large predatory fish is the accumulation of mercury, especially methylmercury," the center said in a statement.
"Methylmercury is the most toxic form of mercury affecting the nervous system, particularly the developing brain. At high levels, mercury can affect fetal brain development, and affect vision, hearing, muscle coordination and memory in adults."
In 2016, WildAid tested samples of raw shark fin samples from Hong Kong and Taiwan's dried seafood markets and found that all contained above the permissible amounts for arsenic and more than half exceeded levels for cadmium, a known carcinogen.
"If something damages your brain, why ... would you eat it?" asked Deborah Mash, professor of neurology at the University of Miami. "There's also no good evidence for health benefits."
A 2016 study by Mash found a cyanobacterial toxin in sharks fins linked to the neurodegenerative diseases Alzheimer's disease and amyotrophic lateral sclerosis, often called ALS.
Analyzing 55 sharks across 10 species from the Atlantic and Pacific oceans, her team found that the majority contained the cyanobacterial toxin β-N-methylamino-l-alanine, together with another environmental toxin -- methylmercury -- which is known to accumulate in sharks.
Traditional Chinese medicine may also have no need for shark fins.
"To my knowledge, shark fin is never a part of Chinese medicine practice," said Professor Lixing Lao, director of the School of Chinese Medicine at the University of Hong Kong. "Chinese medicine community is nowadays very much aware of protection of endangered species to be used in the Chinese medicine practice."
Besides, "shark fins have no taste on their own. It barely offers a crunchy texture when you bite into it," said executive chef Chan Yan Tak, the first Chinese chef to get three Michelin stars, at the Four Seasons in Hong Kong, which stopped serving shark fin in 2011. "The flavor comes from the soup: a superior stock that is boiled for eight hours with Yunnan ham, chicken and pork ribs."
Increasingly, public attitudes toward shark fin are turning.
Pushback from big voices
According to parallel studies in 2009 and 2014, consumption of shark fin in the last year surveyed in Hong Kong went down from more than 70% to less than 45%.
In contrast, the acceptability of excluding shark fin soup from weddings went up from around 78% to 92%, according to studies by the marine environment nonprofit Bloom Association of Hong Kong.
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Dried shark fin are easily accessibly in Hong Kong at the Dried Seafood Market.
WildAid and WWF-Hong Kong estimate that more than 18,000 hotels, 44 international airlines and 17 of the 19 largest container shipping lines have stopped serving shark fin and banned it from cargo, affecting close to three-quarters of global shipments. The volume of shark fin imported into Hong Kong has also dropped by half, from 10,210 metric tons in 2007 to 4,979 metric tons in 2017, according to Hong Kong's Census and Statistics Department.
"It was a big challenge initially, getting customers to accept our shark fin policy," said Andy Chan, senior director of food and beverage for Shangri-La Hotels & Restaurants, which took shark fin off its menus in 2010. "We accepted that it would mean a substantial cut for our banqueting business. We initiated the policy because it was the right thing to do. We recognized that as a species, sharks are threatened with extinction, and if this happens, it would put the health of our oceans and fisheries at risk."
Joining Shangri-La in pledging to stop the sale of shark fin are Cathay Pacific, Four Seasons and, most recently, the popular Hong Kong restaurant chain Maxim's, by 2020. The Four Seasons and some others offer a vegan version of the soup.
"As more hotels and restaurants join together in this pledge, we send a strong signal to our community and can together help to reshape dining concepts around sustainability," Tak said.
WWF and WildAid are working to persuade more companies to make the pledge against shark fin. Recently, WildAid campaigner Alex Hofford talked to the Fulum Group, one of the largest Hong Kong chains with more than 80 restaurants, about reviewing its policies.
Citing the nonprofit's motto, Hofford said, "when the buying stops, the killing can, too."