Hi all, as a Canadian, I'll try to help out
It's a huge country, so similar to the US, different regions vary wildly. Blanket statements don't really sum it up.
Firstly, please keep Celine
My part of Canada is similar to New York state...can be cold in the winter, and hot and muggy in the summer. South BC is fairly warm by our standards year round (freezing/snow is rare).
There is great fishing to be had, usually better as you go further North. Trout, bass, pickerel, pike, and muskie can be found here in the central/east, and salmon are also around in BC (and way north Quebec and Labrador). I wouldn't say most lakes are cold enough for trout, and with temperatures rising the numbers of lakes that can are dropping.
Most of our population is clustered close to the border with the US, as most industry and commerce actually runs north-south rather than between provinces. We have the population of California spread across a landmass bigger than the US, so there are large tracts of uninhabited land, owned by the "Crown" (government, as a commonwealth country the term is a throwback to British colony days). We're generally free to hunt/fish/camp on these lands with appropriate permits and licenses, but getting to the farflung places can be tough.
Ask away!