We, NMFS, issue a final determination to list a Distinct Population Segment (DPS) of the beluga whale, Delphinapterus leucas, found in Cook Inlet, Alaska, as endangered under the Endangered Species Act of 1973, as amended (ESA). Following completion of a Status Review of this DPS (the Cook Inlet beluga whale) under the ESA, we published a proposed rule to list this DPS as an endangered species on April 20, 2007. We subsequently extended the date for final determination on the proposed action by 6 months, until October 20, 2008, as provided for by the ESA. After consideration of public comments received on the proposed rule and other available information, we have determined that the Cook Inlet beluga whale is in danger of extinction throughout its range, and should be listed as an endangered species. We will propose to designate critical habitat for the Cook Inlet beluga whale in a future rulemaking.