collapsed walleye fishery...

[Broad Bill]

https://www.fox43.com/article/news/l...d-7d1c77722b76

My guess would be the same factors that have annihilated the smallmouth fishery which is basically pollution and bacterial infections from agricultural and urban run off. Look at the smallmouth in the link. Combine that with probably warmer water temperatures and the Susquehanna is a sick river system. I read one article which attributed the smallmouth decline to largemouth bass virus which they didn't think smallmouth could contract. If these fish, which share the same habitat and forage as walleye, are succumbing to water quality issues in the Susquehanna, I would bet there's a high degree of probability the same is happening with the walleye population. And if all this means young of the year are dying or fish are becoming infertile, then you're looking at the beginning of the end which Bob from your post sounds like exactly what's happening. We're turning these major ecosystems into cesspools and then we wonder why fish that are dependent on colder temperatures and clean water quality are disappearing.