I read an article on this in a US gun magazine some years ago, most likely Wolfe's
Rifle Magazine.
It made the point that the most likely scenario for man v aggressive bear confrontation for hunters and/or walkers was in close cover where the bear is surprised and feels attack is better than retreat or is a sow with cubs. Given human reaction times, time required to unholster / raise a handgun, the speed a bear moves (frighteningly fast once they decide to attack!), and the short distances involved, the writer's point was that handgun calibre was usually irrelevant as the chance of getting a shot off at all was low to nil. His research said that most successful defences occurred after the bear reached the human and had starting mauling him where the victim had unholstered the gun or was able to do so and push the muzzle against the animal's chest or up against the chin. (No mean feat when in a tight bear hug I'd think!) That of course nearly always left the hunter to walk out of the boonies with serious injuries and blood loss.
Fishing would be a mite different as riversides are often much more open of course.
This is pretty academic to us in the British Isles unless we take north American or Siberian hunting vacations - it's believed bears were hunted to extinction 1,500 (yep, one thousand five hundred, not one-fifty) years ago. There is though a UK television extreme angling show called
River Monsters featuring one Jeremy Wade and normally involving hunting down rare, huge, exotic, ugly and sometimes very dangerous river creatures all over the world.
https://www.google.co.uk/search?hs=...kAhVIWRUIHZK0BfcQsAR6BAgDEAE&biw=1280&bih=622
One episode had him in Alaska autumn fishing for salmon and the 'river monsters' were obviously the brown bears and their adolescent cubs that kept chasing his hooked fish. His local guide had a stainless large-calibre hand cannon. He didn't shoot any bear, only tried to frighten them off with the report from firing in the air. That worked only twice IIRC, the bears soon realising the human wasn't serious, so the line with the fish on was cut, angler, guide and camera crew hastily retreated to a bear free stretch of the river. They stayed with the bears longer than I would have!
