Harpoon

A harpoon is a long spear-like instrument used in fishing to catch fish or large marine mammals such as whales. It does this task by impaling the target animal, allowing the fishermen to use a rope or chain attached to the butt of the projectile to catch the animal. A harpoon can also be used as a weapon.
Typically, a harpoon for fishing has backwards-pointing barbs which stop the fish getting free.