There is lot of discussion on this subject and here are some thoughts.
Light noise makers, like cow bells, are great for awareness. Talking in loud friendly voice or singing is great too. As far as using air horns and what not, I've heard of bears actually be provoked into charging because of how startling a loud squealing blast that they put off. The best thing to do when encountering a bear is to talk in a loud calm voice and slowly back away. Waving your arms and making yourself look bigger while doing this is good too. Stand you ground if you need to, but do not freak out and never turn and run.
Bear spray vs firearms. Firearms are only good if you know how to use them in a close confrontational situation. Statistics show that firearms are less effective for protection than bear spray. We like to go with bear spray. It's easy to use and very effective when used in bear charging situation. Remember that bear spray is only really effective at 30' or less.
Honestly, if you stay calm and collected in an encounter, you'll be fine. When moving from one fishing spot to the next, take your time and make plenty of noise. This will help warn the bears of your presence. Mostly they do not want to be around you and will vacate the area.