Welcome to Pond Boss, Michfish.

I may be wrong on this, but I thought HSB were not allowed in Michigan. I may be totally wrong on that though. Someone correct me if I'm wrong.

They do survive months under ice in my pond in PA with similar conditions to what you've described in yours. I believe they would make it in your pond also without full details.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."