I was bass fishing in a local florida swamp and caught a decent size
one by accident. I got that thing to my canoe, and really, really
wanted my lure back. I'm sitting there looking at this thing that's
all teeth and wondering what to do!
The commercial fishermen, the ones subject to a shark in the net,
carry a shotgun. If you catch one on a line, you cut the line.
For smaller fish, there are clubs designed for finishing them off. You
smash their skull. You can make a nice club from a broken paddle.
Go to your local ball club and ask for a couple of suitable broken
bats. Repair and shorten. Those bats cost a hundred bucks, by the way.