46 U.S.C. § 11109

1. (a)Wages due or accruing to a master or seaman are not subject to attachment or arrestment from any court, except for an order of a court about the payment by a master or seaman of any part of the master’s or seaman’s wages for the support and maintenance of the spouse or minor children of the master or seaman, or both. A payment of wages to a master or seaman is valid, notwithstanding any prior sale or assignment of wages or any attachment, encumbrance, or arrestment of the wages.
2. (b)An assignment or sale of wages or salvage made before the payment of wages does not bind the party making it, except allotments authorized by section 10315 of this title.
3. (c)This section applies to an individual employed on a fishing vessel or any fish processing vessel.