At the back of a second-floor bookshop, past the shelves of Chinese novels and magazines, is a cluttered office from which Patrick Ip has spent the past 42 years running his shark-fin business in Vancouver. Displayed on the wall behind him are dozens of shark fins of all shapes, sizes and colours, hanging from the bulletin board on hooks.

From here, the 75-year-old imports thousands of pounds from Hong Kong and Singapore each year, supplying, by his own estimate, about 90 per cent of the city's Chinese restaurants. It's also where he's quietly weathered the shark-fin controversies of recent years, including attempted bans and protests by local activists.

To him, those days – when he saw a 30-per-cent drop in sales – have passed. "Five years ago, it was a little bit down," he said. "Right now, it's up." He talks about wanting to pass the business on to his children.

Story continues below advertisement

He might not get the chance.

This week, a Liberal MP is set to propose in the House of Commons a ban on the importation of shark fin into Canada, The Globe and Mail has learned. It's part of a three-part animal welfare bill that also restricts the sale of cat and dog fur, and strengthens the Criminal Code surrounding animal cruelty. That private member's bill, from Toronto MP Nathaniel Erskine-Smith, sets the stage for yet another shark-fin fight. Just a few years ago, the issue sparked many hours of debate by local governments across the country, stoking racial tensions along the way.

"Russians believe in caviar, the Chinese believe in shark fin, and the French believe in foie gras," said David Chung, president of the BC Asian Restaurant Café Owners Association and himself the owner of a Chinese restaurant. "It's not for somebody who has no such culture to say it's any good."

Animal rights activists and conservation officials have warned, however, that appetites for the expensive Chinese delicacy have led to plummeting shark populations around the world – an estimated 100 million sharks killed every year, according to conservation group WildAid. As a result, the group says, all 14 species most commonly used in the shark-fin trade are at risk of extinction.

That lobbying culminated in a burst of activity between 2011 and 2013. In that time, a number of cities across the country moved to impose bans – though efforts in municipalities with substantial Chinese-Canadian populations, such as Vancouver and Toronto, were unsuccessful. A ban by Toronto city council was later overturned by the Ontario Superior Court, after the judge decided the decision was outside the powers of a municipality.

In 2013, NDP MP Fin Donnelly proposed a federal ban. That bill was narrowly defeated, but supported by both the NDP and Liberals. The Tories promised instead to strengthen regulations, though no such change materialized.

In particular, critics focused on the practice of "finning" – where fishermen remove the fins, which can be worth hundreds of dollars per pound, and dispose the rest of the body back into the ocean. Canada already bans finning, and the import of fins from endangered species. But in practice, critics say it's often difficult for border officials to determine the provenance of a specific product without costly DNA analysis.

Story continues below advertisement

"You're just relying on industry to say, 'We're good,'" Mr. Donnelly said. Imposing an outright ban, he said, would be an easier way to get around costly checks. Mr. Erskine-Smith's bill this week will echo the language of the 2013 attempt.

The new bill also highlights a curious trend: Educational campaigns on shark sustainability have resulted in a sharp drop in global demand – an estimated 70 per cent in China and 25 per cent worldwide over the past decade, according to researchers. In Canada, demand also plummeted in 2012, but since then – with the issue somewhat out of the spotlight – that number has again crept up, from 233,000 pounds in 2012 to 318,000 pounds last year.

On a global perspective, Canada is still a small player – the largest importer outside of Asia, but less than 2 per cent of global trade. Despite this, Mr. Erskine-Smith said it's still a cause for Ottawa to pursue. "It's obviously an offensive practice to most Canadians to be cutting off the shark's fin and throwing the remainder of the body into the ocean," he said. "It's not just cruel, it's also obviously wasteful."

But to Canadians like Mr. Chung the issue is not so clear-cut – and one best left alone.

For Mr. Chung, the debate several years ago in Vancouver was a bruising one. Because he represented owners of Chinese restaurants, he found himself one of the few outspoken opponents of a ban, and engaged in a very heated war of words with a local Chinese-Canadian politician.

"Oh no, we're still there?" he said when asked about the shark-fin controversy. Neither he nor Mr. Ip was aware during their interviews of the coming Ottawa bill.

Story continues below advertisement

Mr. Chung said claims of "finning" as widespread in the industry are overblown, pointing to shark meat and cartilage powder as evidence that other parts of the fish are used. New markets for shark meat in Italy and Brazil have emerged in the past decade – with trade increasing by 42 per cent from 2000 and 2011, according to the Food and Agriculture Organization of the United Nations.

To Mr. Chung, the issue is not business. He said shark fin has never been profitable for restaurants, because the expensive ingredient means food costs make up about 60 per cent of the menu price. Rather, he said, the issue is cultural sensitivity.

Like champagne, shark fin has long been associated in Chinese culture with celebration – simmered in chicken broth and other ingredients, and served as soup at weddings and banquets. The fin itself has no flavour, but the texture of the individual strands – like glass noodles, with more bite – is prized. Because the soup can cost over $100 per bowl, it's a status symbol, a luxury that an increasing number of Chinese can now afford – a sign for themselves and to others that they've made it.

For Mr. Ip, shark fin is what allowed him to support a family as a newcomer to Canada dozens of years ago, and what helped lift him from odd jobs – as a dishwasher, a driver and a cook – to business owner, and prominence within the local community. He's proud of his knowledge, and how he can point to any of the fins on his bulletin board and determine its quality by sight. He's also proud that, for such a tumultuous industry, he's made it for such a long time.

Does he think this industry will exist much longer?

"I think so," he said, before reassessing. "I hope so."