I’m re-reading Robert Hughes’ Barcelona, a fascinating history of the city from its foundation to the early 20th century. There’s a very interesting section on the Barcelonan and Catalan seafaring tradition in which he mentions the importance of ship’s cats – the bigger and blacker the better – and the custom of Shanghaiing them by tempting them on board with a bit of fish. Under 14th-century Catalan maritime law (Les Bones Costumes de la Mar), ship’s owners were penalised of they failed to provide a cat and rats infested the ship. Here’s the full quote from the law I managed to find:
If good be damaged by rats, and there is no cat on board the ship, the managing owner of the ship ought to make compensation; but it has not been declared in the case where a ship has had cats on board in the place where she was laden, and after she has sailed away the said cats have died and the rats have damaged the goods before the ship has arrived at a place where they could procure cats; if the managing owner of the ship shall buy cats and put them on board as soon as they arrive at a place, where they can find them for sale or as a gift or can get them on board in any manner, he is not bound to make good the said losses, for they have no happened through his default.
from “Les Bones Costumes de la Mar” (14th-15th c. Catalan text) from Twiss, Sir Travers, ed. Monumenta Juridica, The Black Book of the Admiralty