Disclaimer: Ya know, I've never been to Alaska, never kilt a bar, tho I usta want to, but am getting soft in my old age.
BUT I read my first bear attack story in Outdoor Life when I was six, and have been a readin' fool for bear attack yarns ever since.
(Okay, so some might leave the "readin'" and "bear attack yarns" parts out of that sentence.
)
Anyway, FWIW Most recently I finished The Grizzly Maze which is a good recounting of the Tim Treadwell incident and discussion of the relation between big bears and people along with a chapter with a pretty decent discussion of risks, deterents and defense by a guy with Alaska outdoor and PH experience, who, BTW, also made it a point to talk to passel of bear-experienced types for their opinions.
Some observations therefrom:
When they had to kill the bruin that had been feeding on Tim and Amy (might not have been the one that killed them) it took a small fusilade of 12 ga and assorted rifle ammo to stop him.
At bear-encounter distances one shot is often all one gets: bear closing from 25 yrds or less at 25 mph leaves a reaction time in seconds. People have been killed before or just after their one shot.
12 ga slug gun w/hunting sights is favored weapon of rangers and bear-viewing guides.
Study of attacks over time shows that the incidence of bear attacks declines in proportion to size of group. Three or more folks together decrease the chances of attack dramatically, and the incidence of fatal attacks falls to zero at four or more.
Electric bear fences are very effective in keeping bears out of camp, and/or away from your tent. Consensus is that had Treadwell used his, even camped in the dangerous high-bear-traffic location he did, it is unlikely that the attack would have occurred.
Bear spray can be effective, if not used too soon so it dissipates, if not deployed when wind is crossing or blowing toward person spraying.
My humble conclusions: carry 12 ga w/heavy slugs, be with a group as much as practical, use a bear fence.