On and after July 2, 1942, commutation of rations (not to exceed $1 per man per day) may be paid to officers and crews of vessels of the United States Fish and Wildlife Service under regulations prescribed by the Secretary of the Interior, and money accruing from commutation of rations on board vessels may be paid on proper vouchers to the persons having charge of the mess of such vessels; and section 5911 of title 5, shall not be construed to require deductions from the salaries of officers and crews of vessels of the United States Fish and Wildlife Service for quarters and rations furnished on vessels of said Service.