Only negative I’ve heard of, which I’ve seen here, is that they may be able to effect survival of fry. I’m wondering if they are negatively impacting my YP survival, as I’m not seeing as many YP as I used to, and not as many ribbons in the spring.
I catch larger GSH on lures all the time. I’m not putting the larger ones back. They may be too big for my SMB and HSB. Thousands surface and go after Optima when I feed.

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