Carcharus is Latin for dogfish, (deriving from Greek carcharos jagged: Carcharodon, the scientific name for the Great White family, means 'sharp tooth), so could be the origin. Also possible are Austrian German Schirk, sturgeon, or dialect French cherquier to seek, as well as German *schurke" scoundrel or Mayan Xoc. Finding all these in 10 minutes suggests to me that the true origin (whatever it is)is buried in a pile of plausible falsehoods. (I evolved one of my own: could it be a mishearing of 'shagreen' [a leather made from skins of rays or sharks] as 'sharkskin'? Sadly, shagreen, from chagrin untanned leather, seems to be younger than shark.) It is suggestive, though, that the word came into English about the time that British sailors were first sailing to the Caribbean and South Atlantic, where sea sharks are found, while land sharks (lawyers, salvagemen, wreckers, etc) had been around for centuries.

Carcharus is Latin for dogfish, (deriving from Greek carcharos jagged: Carcharodon, the scientific name for the Great White family, means 'sharp tooth'), so could be the origin. Also possible are Austrian German Schirk, sturgeon, or dialect French cherquier to seek, as well as German schurke scoundrel or Mayan Xoc. Finding all these in 10 minutes suggests to me that the true origin (whatever it is) is buried in a pile of plausible falsehoods. (I evolved one of my own: could it be a mishearing of 'shagreen' [a leather made from skins of rays or sharks] as 'sharkskin'? Sadly, shagreen, from chagrin untanned leather, seems to be younger than shark.) It is suggestive, though, that the word came into English about the time that British sailors were first sailing to the Caribbean and South Atlantic, where sea sharks are found, while land sharks (lawyers, salvagemen, wreckers, etc) had been around for centuries.