Sport trotlines must be marked with the owner's name and address and with visible buoys and must be submerged at least three feet below the surface of the water. Such trotlines must be attended regularly and removed after the completed fishing trip. Unmarked or unattended lines will be confiscated by personnel of the department. As used in this Code section, "sport trotlines" means one line or a combination of lines using less than 51 hooks. It shall be unlawful to use any sport trotline within one-half mile below any lock or dam on any of the fresh waters of this state.