I've found that a barbed hook (trebble) is essential when snagging stacked up salmon <kidding>.

Actually I agree with HPB. Esepecially when dealing with flies and light line/tippet situations. A sharp hook with no barb will sink in deeper and with less effort.

When dealing with certain lures (like plugs) where a fish can actually use the lure to pull the hook(s) out, then the barb(s) can help - as long as you have a strong hood set.

99% of the time, I prefer to go barbless. For one, you can remove it from the fish much easier (and anything else that it may hook on - like your pants...).

-Chad