Dale, years ago, I stocked our creek with Redfins. I stocked pregnant females caught from other creeks.
It wasn't long until I had a gold mine. About 6-8 years went by with all the Redfins I needed, then NO Redfins. Zero.
What the heck?
Only thing I could think of the farmer above me dumped chemicals or cleaned sprayer tanks into the creek.
I never re-stocked. But other streams have 'em and weren't affected at that time.