Lake Aquaponics Experiment

This year I attempted to grow plants on a floating raft on our lake in central Wisconsin.  I've been meaning to try it for about 5 years now and finally got around to getting the plants started and built a raft.  There are loads of fish near the shore so I figure there's plenty of nutrients in there.  On my first attempt a muskrat destroyed the raft by climbing on it.  He really broke the thing up.  On my second attempt I built a thicker raft and tied it to the pier.  This worked but the water level of the lake dropped several inches and left the raft exposed for deer to just walk over and eat.  The lake level is always changing since it's a spring fed lake.  When I put the pier back out in 2016 it will be in deeper water.  Anyway, below are videos of my attempts.  Please comment if you have any ideas.