16 USC 742b - United States Fish and Wildlife Service

(a) Assistant Secretary for Fish and Wildlife 
There is established within the Department of the Interior the position of Assistant Secretary for Fish and Wildlife. Such Assistant Secretary shall be appointed by the President, by and with the advice and consent of the Senate, and shall be compensated at the same rate as other Assistant Secretaries.
(b) Establishment; Director of United States Fish and Wildlife Service; appointment; qualifications 
There is established within the Department of the Interior the United States Fish and Wildlife Service. The functions of the United States Fish and Wildlife Service shall be administered under the supervision of the Director, who shall be subject to the supervision of the Assistant Secretary for Fish and Wildlife. The Director of the United States Fish and Wildlife Service shall be appointed by the President, by and with the advice and consent of the Senate. No individual may be appointed as the Director unless he is, by reason of scientific education and experience, knowledgeable in the principles of fisheries and wildlife management.
(c) Succession to United States Fish and Wildlife Service and Bureau of Sport Fisheries and Wildlife 
The United States Fish and Wildlife Service established by subsection (b) of this section shall succeed to and replace the United States Fish and Wildlife Service (as constituted on June 30, 1974) and the Bureau of Sport Fisheries and Wildlife (as constituted on such date). All laws and regulations in effect on June 30, 1974, which relate to matters administered by the Department of the Interior through the United States Fish and Wildlife Service (as constituted on such date) and the Bureau of Sport Fisheries and Wildlife (as constituted on such date) shall remain in effect.
(d) Functions and responsibilities of Secretary of the Interior 
All functions and responsibilities placed in the Department of the Interior or any official thereof by this Act shall be included among the functions and responsibilities of the Secretary of the Interior, as the head of the Department, and shall be carried out under his direction pursuant to such procedures or delegations of authority as he may deem advisable and in the public interest.