Built a pond in Central Missouri three years ago and stocked it April of 2018. Fishing it this year for the first time and having success catching many 13"-14" LMB with several 16". My question relates to scars and wounds on some bass. I began catching fish with vertical scarring just behind the gill plate in a narrow V shape. At first I didn't think much of it. I then found a 14" dead on my bank with wounds on both sides again behind the gill plate. Finally, last night I caught a bass with an open wound with the same pattern except one side appeared to have been impaled. I have seen Great Blue Herons around the pond. The area also has River Otters and we have constant snapping turtles. My gut tells be GBH due to scar shape. Any ideas and remedies for the issue. Thank you!

Apply SSS rule to the heron.

Those are cormorant scars, I'm 100% sure. Some of my LMBs have the same scars, as you can see in the photos at the bottom of this thread http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=503926 .
The heron hits like a bullet and leaves circular holes.