Seems like an adaptation of the word piracy, probably to make the word more compact. "Seeräuber" - another german word for pirate - translates to "sea-robber",

Seems like an adaptation of the word piracy, probably to make the word more compact. "Seeräuber" - another german word for pirate - translates to "sea-robber", and I've never heard of pirates sneaking onto boats to make copies of things without leaving a trace.