Thanks for the suggestions. It’d be easy to solve if I knew what was causing it,and eliminated it. I could back my Jon boat into the pond, and not take it off the trailer. I may give that a go, if it’s not better next week.

9 yr old pond, 1 ac, 15' deep.
RES, YP, GS, FHM (no longer), HBG (going away), SMB, and HSB (only one seen in 5 yrs) Restocked HSB (2020) Have seen one of these.
I think that's about all I should put in my little pond.
Otter attack in 2023