Whoever, being the master or owner or person having charge of any vessel, receives on board any other person with the knowledge or intent that such person is to be carried from any place within the United States to any other place to be held or sold as a slave, or carries away from any place within the United States any such person with the intent that he may be so held or sold as a slave, shall be fined under this title or imprisoned not more than 10 years, or both.