No person shall act as a longshoreman or as a checker within the Port of New York District unless at the time he is included in the longshoremen's register as a longshoreman or checker, respectively, and no person shall employ another to work as a longshoreman or checker within the Port of New York District who is not so included in the longshoremen's register. No person shall act as a telecommunications system controller within the Port of New York District unless at the time he is registered by the commission as such, and no person shall employ another to work as a telecommunications system controller within the Port of New York District who is not so registered by the commission.