The purpose of this legislation is to update the Endangered Species Act of 1973 by transferring certain responsibilities related to specific fish species from the Secretary of Commerce to the Secretary of the Interior. This change focuses on two types of fish: anadromous species, which spawn in freshwater and migrate to the ocean, and catadromous species, which spawn in the ocean and migrate to freshwater. Key provisions of the legislation include the official transfer of functions concerning these fish species to the Secretary of the Interior.