I have heard of them in there, Mostly in or around the Spokane arm. There is a big lake right below Roosevelt that got a huge plant of them a few years back, sterile ones like triploids. Did some research and they want them to stay put, was the reason they were sterile. We caught several last year walleye fishing and they were running 4 to 5 Lbs. I plan on targeting them this year some, they should be, I hope 6 plus this year.