The forfeitures provided for in this chapter shall be payable into the Treasury of the United States, and shall be recoverable, except as otherwise provided with respect to a forfeiture penalty determined under section
503
(b)(3) of this title, in a civil suit in the name of the United States brought in the district where the person or carrier has its principal operating office or in any district through which the line or system of the carrier runs: Provided, That any suit for the recovery of a forfeiture imposed pursuant to the provisions of this chapter shall be a trial de novo: Provided further, That in the case of forfeiture by a ship, said forfeiture may also be recoverable by way of libel in any district in which such ship shall arrive or depart. Such forfeitures shall be in addition to any other general or specific penalties provided in this chapter. It shall be the duty of the various United States attorneys, under the direction of the Attorney General of the United States, to prosecute for the recovery of forfeitures under this chapter. The costs and expenses of such prosecutions shall be paid from the appropriation for the expenses of the courts of the United States.