It is often interesting to dipnet up here (Alaska) for salmon....not really sport fishing, more of a meat haul, but one always runs the chance of missing the run during the 1-3 day opener.
Anyway...when you bring in a limit of 30-60 fish (not many silvers, but reds and some kings), it is interesting to see just what tribulations the salmon can survive and still make it upstream: lots of faint striations? That one got out of a net; just flat missing a chunk? Bear or seal escape artist. Odd notch or missing small fin? Hatchery fish that got confused. Deep regular gouges; again, bear, seal, possibly Beluga escape artist. (infrequently on the dipnet areas): Salmon with a hook embedded in it's back or even in the underside? Got out of a snagging situation.
Again, salmon are tough: surviving those situations and retaining enough strength and drive to make it several days upriver from the saltwater.