The Secretary of the Interior is authorized to cooperate with the Secretary of Agriculture of Puerto Rico, the Mayor of the District of Columbia, the Governor of Guam, the Governor of American Samoa, the Governor of the Commonwealth of the Northern Mariana Islands, and the Governor of the Virgin Islands, in the conduct of fish restoration and management projects, as defined in , upon such terms and conditions as he shall deem fair, just, and equitable, and is authorized to apportion to Puerto Rico, the District of Columbia, Guam, American Samoa, the Commonwealth of the Northern Mariana Islands, and the Virgin Islands, out of money available for apportionment under this chapter, such sums as he shall determine, not exceeding for Puerto Rico 1 per centum, for the District of Columbia one-third of 1 per centum, for Guam one-third of 1 per centum, for American Samoa one-third of 1 per centum, for the Commonwealth of the Northern Mariana Islands one-third of 1 per centum, and for the Virgin Islands one-third of 1 per centum of the total amount apportioned in any one year, but the Secretary shall in no event require any of said cooperating agencies to pay an amount which will exceed 25 per centum of the cost of any project. Any unexpended or unobligated balance of any apportionment made pursuant to this section shall be made available for expenditure in Puerto Rico, the District of Columbia, Guam, the Commonwealth of the Northern Mariana Islands, or the Virgin Islands, as the case may be, in the succeeding year, on any approved projects, and if unexpended or unobligated at the end of such year is authorized to be made available for expenditure by the Secretary of the Interior to supplement the 58.012 percent of the balance of each annual appropriation to be apportioned among the States under .section 777a of this titlesection 777c(c) of this title