That is interesting. I enjoyed that video.
I have been fishing in the same lake in Vermont for 40 years and I am certain there are less fish than years ago. So I wrote the Fish and Game in Vermont and learned that the fish they stock has their fins cut as shown in this video.
Here is one paragraph from the email they sent me.
As of 2006 we discontinued stocking lake trout (yearlings stocked in the spring in the 6”-8” range). Since 1994 we had removed the adipose fin from all lake trout we stocked, so we could recognize them as being from our stocking when they were caught later. Based on angler reports, our direct observations capturing fish, and by examining anglers’ fish during our “creel surveys”, it appeared that very few of the stocked lake trout were showing up, while nearly all the ones that we examined had the adipose fin, meaning they were the result of natural reproduction. Seeing no direct angler benefit from the lake trout stocking, we suspended it. We expect that the discontinuation has virtually no bearing on the size of the lake trout population and anglers’ lake trout catch.
Guy