A long time back (i.e. when I was a kid, which was a long time back), you could get a visa to come to Canada if you invested a certain amount of money into a company and ran that company for a few years (2 was the minimum, I think). For relatively well off people in China this was a great opportunity and basically the default thing to do was to open a Chinese restaurant. Lots of these restaurants went under after the proprietors got permanent residence status, but a suprisingly large number of them stuck around. My good friend's father was one of those immigrants and he said that he had no interested at all in running a restaurant, but after doing it for a few years he found that he really enjoyed it. So historically there have been a lot of Chinese restaurants in Canada and a large population of Chinese Canadians. Over time, quite a few of these restaurants have gotten very good and the owners hire famous chefs from China to come over and cook in them (at one time that was a thing you could do... I'm not so sure any more). Because of this, famous Chinese dishes started to appear in the restaurants. Again, when I was a kid, most restaurants had 2 menus: one in Chinese and one in English. The English one had "Chinese Canadian" food like sweet and sour pork balls in neon red sauce, while the Chinese menu had actual Chinese cuisine. As Canadians became more aware of this, they started preferring the Chinese menu. By the time I was in University, everybody I knew wouldn't dream of ordering off the English menu (I grew up in Winnipeg, which had a very good set of Chinese restaurants at the time). Again, over time, Canadians started to appreciate fine Chinese cuisine. One of the dishes that is popular is shark fin soup. That's basically the long and the short of it as far as I can tell.
Canada has a relatively large (~5%) Chinese and Chinese-Canadian population. A large immigration event happened during the 90s due to the uncertainty surrounding the UK handover of Hong Kong[1] and many resettled in Vancouver.
The number of Chinese immigrants to Canada cannot be underestimated. There are whole cities where Chinese constitute more than 50% of the population [1].
