Now I got one question: is hunting a reliable source of meat? Correct me if I'm mistaken, but from as far as I know not all these animals that you've mentioned are readily "hunt-able" yearlong.
Yes, and that's to ensure that animals don't become endangered. Look at whales. People hunted them for meat and oil for hundreds of years and still do to this day, and had many governments not put a ban on whaling, they would be extinct.
The same is true with any animal. Hunting is fine, but killing animals year round would not give them a chance to regrow in the population that some hunters have killed off.
There are some animals where I am from though that you are allowed to kill anytime, mainly coyotes.
No regulation on the kind of gun you need to use, what time of year, size, or anything of that. If you see a coyote, you can kill it, right then and there. (this is because they are pests though, not because they are hunted for meat)