Ask those that participated in the Snider Creek Brood Stock program on the Duc, if it was working or not. Although no scientific documentation took place, those early wilds that showed up the end of Dec. into January sure were fun to grapple with. I think today were still seeing some positive early returns from those efforts.
https://wdfw.wa.gov/sites/default/files/publications/01187/wdfw01187.pdf

I volunteered on the Carbon/Puyallup brood stock program back in the late 70's & early 80's. Although not documented, we also were seeing positive results before it got shut down.