Great time for a bear discussion! When the rivers fill up with fish they will come after the fish just as we will. We will probably all be bumping into a few of them over the next few months.
I have lived, played and worked in the wilderness for years (BC, Alaska, Washington and the Yukon). I have survived lots of bear encounters with only 1 close call. I would like to offer a few comments on bear aware issues.
1) Make noise: as others have said surprising bears is a bad thing. If you are with buddies a good heated conversation should do if you are alone sing a song or if you are like me and don't sing well just yell "hey bear". The amount of noise I make depends on how far I can see: if I am on a trail through a dense riparian area and can't see far I will make noise almost constantly. If i am on a gravel bar or in an open forest with decent view scapes I will make noise less often.
2) Look for signs: do a google image search for bear scat if you don't know what it looks like. Always look for scat and poke it with a stick to see how fresh it is. If you are in an area with a tonne of scat make more noise and be extra carefull. Other bear signs to look for are dug up ground ripped up logs, prints and scratches on the trunks of trees. I was on a trib of the Skeena last year coho fishing and saw grizzly scratches that were 12 feet up a tree and the ground was absolutely covered in fresh scat needless to say we were loud and had the spray ready!
3) Dawn, Dusk and Dark: bears will travel and forage heavily during these times also your visibility will be limited be extra carefull and make lots of noise at these times
4) Grizzly vs Black: Learn to tell the difference check out ID characteristics. Grizzlies will usually only attack out of aggression to prove their dominance if they feel threatened this type of attack is when you should play dead. Blackies will attack with predatory intent never play dead with a balcky make yourself look big and if that doesn't work fight for your life!
5) Carry spray: I carry a bottle on my wading belt if I am going to an area where I feel I will need it. When in Skeena country, Alaska or the Yukon I will often be strapped with a canister on each hip. I have never sprayed a bear and have only talked to one person who ever has and he said it worked well.
Alwaysfishin: I would be very interested to hear stories about the times you have had to spray bears especially the time it didn't work! It would be very cool if you could share those experiences IMO.
6) If you see a bear and it sees you: back away keep your eye on it but don't look it directly in the eye make noise so it can ID you as a human not a wounded deer or something
7) If you see a bear and it hasn't seen you move away from it quietly

Climb a tree? blackies can climb trees well so can small grizzlies I do not think I would climb a tree (it would be hard to judge a small from a large grizzly as you are trying to find a tree to climb). not sure why the cool guy smilie poped up instead of an 8
9) Find more info there are some great bear awareness videos out there maybe try looking at the ministry of environmet website to see if they can be ordered
10) Stay calm: this is the best thing you can do during any bear encounter although the ability to stay calm can only come through experience.
11) Danger situations: Surprising a bear (make noise), mothers with cubs (give them alot of space and extra caution), young bears (curious and inexperienced as previously posted by alwaysfishin), protecting a kill (if you see a dead animal on the ground get away from it there could be a rightfull owner near by ready to protect dinner)
Hope that helps, good luck this fall and hopefully we all see some bears but from a safe distance.