Wherever, in the statutes of the United States or in the rulings, regulations, or interpretations of various administrative bureaus and agencies of the United States there appears or may appear the term "products of American fisheries" said term shall not include fresh or frozen fish fillets, fresh or frozen fish steaks, or fresh or frozen slices of fish substantially free of bone (including any of the foregoing divided into sections), produced in a foreign country or its territorial waters, in whole or in part with the use of the labor of persons who are not residents of the United States.