if you're fishing on any chum or salmon bearing rivers in the fall, expect to hook into some chums, targeting them or not. everyone knows generally chum will pull and pull and pull, until they, you and your rod and gear, including your line are worn out.
I don't know why anyone would go lighter then 10 or 12 lb test fishing for salmon, especially near rapids at that!
I think it's pretty obvious you need to beef up your whole set up if you want to fish where you were fishing and not expect to lose alot of line and gear to chums.
12 lb test for leader should be fine, however, if there's lots of chums around, and unless you're short floating or using a jig, fouling them is innevidible. in this case might as well save yourself alot of time and strain on your gear (and the fish) and snap the thing off.
Bottom line is, if you're fishing anywher near chums expect to hook into 'em and expect to lose some gear...this talk of 6 or 8 lb test while chum fishing imo is puzzling. I'm sure lots of people have landed chums on light gear, but original poster I beleive is looking for advice on which lb lines he should be using when knowing he's likely to encounter chums...