Otters...GRRRR!! While neat to see and cute to watch, they will seriously degrade the fishing in your pond(s)...and usually in a matter of days. If they just killed fish to eat them, maybe it wouldn't be so bad. But they kill and kill and kill and kill and eat a fraction of them. Short version...I had them in my big pond at my farm and the fishing nowadays is a shadow of the past. I now have a nice pond, still filling up, behind our new house and while it has been stocked, the fish are still pretty small. But that will be my "fish pond" of the future because when Mr. or Mrs. Otter show up there, and they will, they will be in comfortable range of my .17 cal...if you know what I mean.
I will be shooting them there even if the DNR is on my deck with me telling me not to. These beasts will kill thousands of dollars of fish in a few days. If you think that you are far enough away from a river system that they will never reach you...think again...they will somehow travel miles over land to get to your pond eventually. Nature abhors a vacuum.

If your pond does happen to be anywhere near a river system...forget about it...they're there.