After guiding in Alaska for a number of summers, and fishing down here my whole life, I have to agree with you. Those fish up there are completely different. I think one reason is like you said--sheer numbers, which means more fish to bite, plus the group mentality that increases aggression. But I also have another theory that may contribute: We have been sport fishing down here for a hundred years of pretty intensive pressure. Over this century, a huge percentage of the aggressive fish (biters) have been taken out of the gene pool. Contrast this to the small percentage and shorter history of hook and line angling in Alaska, and you have a gene pool that still has the aggressive chromosomes in it. Anyway, just a theory, but it seems to make sense.