(a)  Prohibitions.⁠—Except as provided in subsection (b), an American Great Lakes vessel may not be used to⁠—

(1)  engage in trade⁠—

(A)  from a port in the United States that is not located on the Great Lakes; or

(B)  between ports in the United States;

(2)  transport bulk cargo (as defined in section 40102 of this title) that is subject to section 55305 or 55314 of this title or section 2631 of title 10; or

(3)  provide a service (except ocean freight service) as⁠—

(A)  a contract carrier; or

(B)  a common carrier on a fixed advertised schedule offering frequent sailings at regular intervals in the foreign trade of the United States.

(b)  Off-Season Exception.⁠—An American Great Lakes vessel may be used for not more than 90 days during any 12-month period to engage in trade prohibited by subsection (a)(1)(A), except during the Great Lakes shipping season.