dodgy bass mouth?

[D'n'A]

I caught this bass a while ago and whilst netting it i thought it looked a bit strange. We then realised its top lip was fully missing.
Has anyone seen this before or know how this could happen?
We thought maybe someone could have been yanking it a bit hard when it buried them in the timber n ripped it off or maybe a genetic disorder?
Sorry you can't see it very clearly in the pic.
If you know anything about this let me know.
cheers, D'n'A.