Pleased to report all koi present and accounted for this morning! Apparently the few hiding places I do have in my small pond worked for them! Thank you all for your concern.
We have numerous bears in the area. I think there over 7,000 in Western NC, if memory serves. In our community we have a momma bear, two cubs, and several males that frequent the neighborhoods. On my street there are three houses going up with large dumpsters where the workmen deposit leftover lunches, snacks, etc. Hard to keep the bears out of these.
I have been very lucky that this is the first time in 3 years a bear has actually been in the pond that I know of. But I knew this might be a problem and the pond was somewhat designed to keep bears at bay.
What I think happened yesterday is typical bear behavior with manmade (and probably natural) ponds. They're not somuch after fish, as they are to cool off in them. And that's what I think I saw. I believe when I came out he rose up on his hind legs from a sitting position and went straight up the bank past the swing and into the woods. He loosened some rock into the pond in the process. No damage to the liner as far as I can tell, but I have filled the pond up and will see if there is more water loss than usual today.
I'm sorry I couldn't get a shot of the bear making his escape!