937. Certificate of compliance with this Act

No stevedoring firm shall be employed in any compensation district by a vessel or by hull owners until it presents to such vessel or hull owners a certificate issued by a deputy commissioner assigned to such district that it has complied with the provisions of this Act [33 USC 901 et seq.] requiring the securing of compensation to its employees. Any person violating the provisions of this section shall be punished by a fine of not more than $ 1,000, or by imprisonment for not more than one year, or by both such fine and imprisonment.