Brown Trout Bird Attack, Burn-like Marks

I am curious what happened to this fish but it seems for sure a bird had a hold of it at some point.

The wildlife you run across and scenarios where you can only assume what happened are common in this area. This Brown Trout was a good size one and had a run in with a bird. Then as you watch the video you will see what looks like burn marks. Black marks. The lady who touched the fish said it seemed warm and it was in the water which was cool so maybe it was recent. What would make the black marks though?

We were fishing in that area just a few days before and didn't see any signs of this fish.