Sharks are in the ocean, so are lions, tigers and bears
Right now the areas I fish are plagued with pesky seals I would personally be more worried about one of them snatching your catch.
After you gaff your fish and secure it with a game clip I usually pull a gill at first and throw the fish back in the water to keep the death as humane as possible and the fish basically swims it out and dies as opposed to flopping out on the deck.
See Exhibit A.
I also have decided that I really like ripping all the gills out right after death and keeping things real nice and clean, the quality of the meat only improves.
And remember to Gut it and Ice it.
I hope this helps, although the photo is from March.
Exhibit A: