They spawn a few weeks before ice out, and a little time after ice out. About a month before ice out, they will begin gathering in shallower, and closer to spawning areas. I'm assuming that far north, ice out is often late in april, maybe early may. Late march I would expect them still deeper. They will probably be on some structure near creek mouths, maybe even in the mouth of bays. You can probably find hammer handles in the bays all year.