Possible reasons:

Shoulda put his client's on better fish
Random vandalism
Pizzed off the wrong fisherman
Another guide is jealous
A woman

I guess there are a thousand other reasons but whoever it was is a POS COWARD for doing it instead of a face to face meeting and working it out like 2 men should. I'm not talking about an azz whuppin but a meeting to hash it out, but if that's what it boils down to...