I was wondering if LMB could survive in a 1/2 acre marsh, the marsh has a deep area of approx. 3ft. On average, I'd say the depth is 20" There are no other fish in the marsh, but the body of water is loaded with frogs, tadpoles and crayfish. I'm in southern Indiana....main concerns are warm and shallower water in the summer and 6-8 inch ice in the winter.

I'm putting about 10 Bass (12-14") in the marsh to control the frogs and crayfish, will also add about 15 channel catfish.

I have seen LMB survive in some nasty holes. There is always the chance of winter kill and perhaps summer kill. There was an small farm pond on a college friend's family farm. It had been there since the 1920's and had filled in so much that it was only about 3 feet at the deepest and most just mucky shallows. There were still bass and BG in the pond. All rather stunted and probably rather genetically inbred from tens of generations of inbreeding. This was in central PA where the winters are probably much like Inidiana.

Don't know about LMB surviving but take a look at these http://www.youtube.com/watch?v=QEJhG_1eEjo I'd be scared to go into the marsh with these.