I'm of two minds... the dog was just being a bear, hunting its' prey, and doing an admirable job, It was showing great restraint by holding only the fins... I'm impressed and want that dog as my hunting buddy. Very good dog. And justifiably proud of himself, as he should be.
The guy, on the other hand, should have controlled his dog, and ought to face fines. The problem now is, the very good dog will go fishing at every opportunity, as he was both successful, and the boss encouraged him with praise.