One of the rules of the nineteenth-century whaling industry was that if a captured whale carcass were lost by its owner, it thereafter became the property of the first ship to recover it.  After being killed, a whale had to be secured to the side of the whale ship, or towed with ropes; and it occasionally happened that the prize would become untethered from its owner, and float away upon the open ocean.  In those cases, the first hand to plant a harpoon in the carcass could claim it as his own.