Welcome to the forumn, I have never fished the Catt, lake michigan tribs only in Michigan, Wisconsin, and Indiana.
The site below will show you the patterns for lake erie tribs all of which many of which are also used through out the great lakes.
This site shows you how to tie them also.
In the spring though nymph and egg/yarn flies are always effective and sometimes streamers or speys can be effective.
Most important you are going to have to get your fly down to the fish which are laying just above the bottom, they will not normally move far for your fly so if it does not get down to them you are just getting casting and mending practice.
I learned that the hard way in 1980 when I took up steelhead fly fishing. I had been a trout fisherman prior to that.
Good luck, you should pick up one of the GL steelheading books also which are now out. There is one specifically on lake erie tribs I was looking at borders this month. It talks in detail about lake erie tribs and has good overall information.
There are other books also.
Shoot me a PM if you need more information.