Had a can of bear spray explode on me once and it completely shut me down for a good forty minutes. I've seen video of it turning bears as well, and as previously noted when using an aerosol you've got to keep wind direction in mind - kinda difficult to do if a bear's charging you. There is also the factor that if you accidentally spray yourself along with a bear, the bear is going to recover first. Also recognize that aerosols are fragile mechanisms and won't stand up very well to daily abuse in the field for extended periods of time. Trust me on that one. And completely forget about bear spray if you're traveling by aircraft - an uncontained accidental discharge is going to bring the ship down.

I've spent the better part of five years living/working in bush Alaska and Desperado's absolutely correct - Remington 870 with slugs would be my first option. Actually, I'd want two people with 870's watching over me while I work, but logistics normally require that we work alone. I'd also not be able to do my job with a longarm, and if needed I promise that it'd be leaning up against my pack. I'd never recommend a sidearm for bear defense, but anything on you is better than not having it all. Life's a compromise, right?

With that in mind, I know a guy who "deterred an attack" from (shot off him) an adolescent grizzly with a .41 magnum - a meager bear gun at best, but it saved his life since it was on him and not with his pack 20 meters away. He's also extremely lucky to be alive since the bear had almost certainly never seen a human being before and didn't know what to expect - it was being cautious and on being shot, the bear ran.

MDinana: Bears normally don't come out of hibernation until late April or May up there...the qualifier being "normally." I'd be very surprised if you ran into one during March, but the possibility exists. PM me a mailing address and I'll pass you a copy of "Staying Safe in Bear Country." It's been mentioned in several threads (including this one) and it's solid information.

Required reading for people in bear country: Herrero's "Bear Attacks - Their Causes and Avoidance."