Some of what follows is from memory and may not be completely correct. I think it's fairly close though.
I think the Commission had a Coho program in conjunction with 3CU. In the mid to late 70's, I think
I think it may have been discontinued because: 1) the salmon (as they have elsewhere..) brought out a somewhat unsavory element of the angling public and things got a little zooey, and 2) I don't think they were getting a return on the smolts that would justify the effort/expense. Some of this, as I recall was blamed on the walleye, who chowed down pretty heavily on the smolt.
I also think a few of the clubs that were/are a loose part of 3CU kept at it with Chinook smolts well into the 80's and that eventually was abandoned as well.
My view was always good riddance to the salmon. The steelhead were sufficient and the salmon became a form of overkill, IMO..
Probably 15 or more years ago, I *think* I recall Bob Hetz of 3CU telling us at a TU meeting in Erie that somebody had taken a Pink (Chum) Salmon out of one of the tribs and there had been a scattering of others. I'm not sure though. So far as I know, the only lake with an active (any time recently) program for Pinks was Superior and that was a while ago, again IIRC.
So, it would have been possible for a Pink to end up in a PA trib this way given that I (again) *think* that the first steelhead that started showing up in Lake Erie were thought to have come down out of the Soo Rapids in the middle part of the last century.
I have no idea why a brown trout fishery has not developed other than to speculate that the right strains have not been tried. Certainly, with the number of catchable yearling browns the Commission puts in Elk alone each spring, the exposure is there. I know some browns are taken each year, but I don't know where they come from. Other than originally from Europe...
I don't mind it as is though.. I mean, where would they go? There's barely enough room in the creeks to hold the steelhead as is..
Enough is enough, IMO.