First, just to correct oscar, it's not the mouth, but it's legal to keep anything hooked above the gillplate.  Now, I will say I find it by no means sportsmanlike to snag a fish.  What's the point in it?  If you're a subsistence fisherman, yes by all means snag away.  I feel if it's your only way to feed your family then I feel family comes first.  But, unless you live in remote Alaska, I don't see it here in Washington in the new millenium. The point to fishing is to have fun, try to FOOL a fish into hitting what you're throwing it, then playing it in (then release or keep if legal to do so).  I've had many a times that I could look into a hole and see fish not biting.  Of course it would have been easy to snag it, but what would that have proven?  Would I be a better fisherman for it?  No, it takes no morals to snag a fish.  Have I snagged a fish, yes, but not on purpose.  The fish was immediately released upon landing (man is it hard to land a tailhooked salmon).  I'm not sure about punishment.  I feel maybe first times a warning, maybe a small fine.  If you get hit another time, then maybe go with the picture in paper.  But, I can almost guarantee you this, most snaggers haven't purchased a license in the first place.  Well, that's all I have to say......
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you haven't lived til you're rowed a cataraft.  Friends don't let friends run Outcasts.