Buddy of mine was out for 3 hours on 4/15 and was shut out jigging. Said that he was marking fish though. I think we still need some warmer weather. My grandfather used to say "liliacs in bloom, walleye go to there doom"
It's a bit early for walleyes but my brother and I were up just above Marine City and caught a couple salmon on jigging spoons last Sunday afternoon. Marked a lot of fish and shad were cruising the surface. Water temp was 40-42 degrees.
If you launch out of the DNR ramp at Marine City be careful, keep your motor trimmed way up as it is very shallow.