Well, since I'm up at this late hour, and Tim must be played out, I'll throw out some info about Salmon and Steelhead here in Washington.
The wild ( native ) runs of fish are seriously depleted, due to many reason. In some rivers/streams/tributary's the numbers are shockingly low.
So the Wildlife/Fisheries Department, along with with Indian Tribes, release many thousands of hatchery reared fish. Those are marked by the removal of the Adipose fin ( tiny fin on back, ahead of tail ). Now there is a job that must rate only second to "Chicken de-beaker".
Soooooo, wild ( native ) fish are returned to the water, and hatchery fish can be kept.
Any yes, it is obvious to any Fisheries officer what an old removed fin stub looks like, compared to a just-caught wild fish that some clever person hacked off its fin in an attempt to keep it.
Mark