I put it in the mosiac and could not get a good image. It looks likeyou were turning and thats why its distorted. It may just be a false image. You can get some crazy stuff when the transducer is not moving in a straight line, and according to your path, you did a 180 right at this point. Your speed was also between 0-0.4 mph. You need to be moving at around 3-4 mph to get good images.
Also, if you notice, the shadow is in reverse. It would be to the left of the image if it were sitting up off the bottom.
I would mark the coordinates and go back and get a better image. Keep the boat moving in straight line to keep from getting curved or distorted images.
Here is a little better image showing speed, gps, and the reverse shadow.
Robert