Everything changed the moment when early French explorers realized, "Well, they don't have any gold, but damn! Those rodents would make good looking hats." Beginning in the 16th century, the fur trade was the backbone of the colonial economy and major international industry for roughly 300 years. The fur trade was instrumental in the development of the country that would become Canada. At the heart of the fur trade was the beaver, whose pelts were used to make everything from wool felt hats to robes to winter coats.
Given the history of companies and governments using the image of the beaver for representative and monetary purposes, as well as the fact that the beaver actually lives in every province, it is not hard to see why the beaver was given royal assent on March 24, 1975—thereby making them Canada's official national animal.
The only reason the beaver is still around today is because of an extensive conservation effort over the course of the 20th century. By the time the fur trade industry collapsed in the middle of the 19th century, the beaver was close to becoming extinct.