This is the third one I have found in the last 10 days.

The scavenger birds have been very frequent visitors so no telling how many I haven’t seen.

The discoloration says to me they were dead when pulled up onto bank, but I may be wrong.
Not a good answer to your question.. Any other species showing up?

Just the last of the big tilapia several weeks ago.

Could be that a disease of some sort has gotten a hold on some of the fish. Not being real familiar with your regions water temps, there are certain viruses and fungus that can be very active between warm and cold seasons.

Can you find a fresher one that hasn't been chewed on?

Looks like a young otter kill to me. Look for slides, scat with scales, and other evidence.

I will look Bob.

FWIW, my pond is heavily frequented by a pair of Bald Eagles, one juvenile Eagle, a pair of Cara Cara, numerous Cranes and now the Cormorants.

The bass I saw on the other side of the pond the Cara Cara were eating and the buzzards were waiting their turn.

Sounds like your pond is already a giant bird feeder. I hope it is not also turning into a giant otter feeder!

I assume we are nearly to the end of the "cold stress" and winter "oxygen stress" period for the fish. For the experts: Are there any disease/fungus vectors that typically exist in the pond, but only become lethal when the fish have been significantly stressed for an extended period?

If so, is there anything we can do as managers to mitigate either the stress or the subsequent lethality?

I'm not Bob, but he's the one that says happy water, happy fish, and I strongly believe that is fact. That being said, there are pathogens and other items present that CAN affect fish if they become weak or stressed for water quality issues that include weather changes, low DO etc.. I hope Bob agrees with me on that much. Otters and other critters might qualify as external or mechanical stress factors that could damage or weaken fish if not killed point-blank.

I do agree with Kenny about pathogens and other things that cause issues with winter time fish health.

Stressors are significant. If fish, cold-blooded as they are, have to try to move quickly in cold water to escape from being eaten, and do that over and over, that's definitely a stressor. Heck, that's a stressor in summer as well. But in winter, if a fish is compromised, bruised, injured, poked, chased into brush or something, it out protective layer can be compromised. If slime is scraped, skin injured, muscles bruised, that opens the door to bacterial attack. In cold water, fish can't heal as readily as they can in warm water, so an infection can spread over a fairly short period of time. When infection manifests on the surface of the skin, and it doesn't heal quickly, saprolegnia attacks. Saprolegnia is that gray, mossy-looking fungus that attaches to the fish. When the fungus hits, the fish is pretty much gonna die. It's not the fungus among us, it's the chase/stressors of environment stuff that starts the process.

My original question was about opportunistic pathogens that are only able to flourish when the fish are stressed.

I never even contemplated stress due to predation attempts. Switching from apex predator to prey is certainly a huge lifestyle change for LMB.

After reading the comments, I can now understand how a raft of otters chasing and grasping fish would cause mortality in the ones they eat, but also in the fish they injure and stress.

The birds may then compound the problems by eating the stressed fish after the otters depart.

Birds can be the primary problem too. I did a population sample in a 5/8 or 3/4 acre pond a while back, very poor visibility - 12" or so. 5 cormorants had taken to visiting the pond daily before I did the study. 80% of the fish that I caught had marks on them and scales missing from where they escaped from the cormorants.

The pond is very clear at present due to the lack of rain. I figured that would give the predators an advantage. The lack of rain may also be making the water stale.

Thanks for adding the "80%" quantification for bird damage that was short of lethal.

I have read lots of posts about birds and otters getting into ponds and wreaking havoc.

This thread was the first (that I noticed) that talked about all of injuries and damages from predation "near misses". Frankly, I find your 80% damages number to be shocking!

I believe Tbar's pond may be too large to string the necessary bird defense lines across the surface.

He said he currently has cranes, Cara Cara, and cormorants at his pond.

Has anyone developed some aqua-shade type product to make a pond so opaque that the avian predators (otters also?) will move on to greener pastures?

I would envision a product that lasted a week, rather than was formulated to be long acting. Would a short-term blackout in the pond disrupt the food chain, BG spawn, etc.?