It has been for quite a while….around 15-20 yrs. My basis for that comment is my experience with angler use and harvest studies in SE Pa. It became particularly obvious when doing such a study on a urban stocked trout stream section in the early 2000’s (Jordan Ck in Allentown) and mentally comparing that to what I had seen on another urban stocked trout section (Wissahickon Ck in Philly) back in about 1990 when harvest was king. On a different stream, Perkiomen Ck, (at Palm and East Greenville) just as an example, in the 1988 angler use and harvest study, somewhere around 80-90% of the preseason stocked trout were harvested in three days. I think there is 1) still a fair amount of harvest over an extended period 2) or else there is a fair amount of C&R mortality added on to lower harvest 3) or else predation, periodic spring warm temps for a few days, and the fact that they are hatchery fish thrown out into a wild environment may cumulatively reduce the stocked trout populations in a number of high pressure streams.
I would add this. If you check this yr’s stocking schedule closely, you will see that many inseason stockings (almost all in the SE) will be completed by the end of April. You will also recall that when the trucks stop rolling, many anglers stop fishing. I think the May fishing on stocked trout waters could be very good this spring and for fly anglers, that means good numbers of fish in the regular stocked trout waters just when the hatches get good. The one hitch to this theory though is that the stockings will occur during the time while many anglers are still trout fishing, so it remains to be seen if the additional active anglers who were often done fishing when the inseason stockings occurred in May will put a pretty good dent in the April inseason stockings.