Chichagof has a huge bear population.  That particular area is not a good place to take tourists on a 'nature walk'.  I really feel terrible for the female guide, that is a terrible experience to go through. I wish her a speedy recovery. She will be haunted by this experience for years to come.   Yes Bear-spray does work.  It is better than most guns at extremely close range.  As a poster mentioned above a bear can move very fast & will overtake any human in a matter of feet.   When I grouse hunt I used to take the .44 but the last few years I've left it at home and have taken bear spray along with the shotgun.