Pursuant to its authority under the Endangered Species Act of 1973 (ESA), NMFS issues this final regulation to require fishing vessels subject to the jurisdiction of the United States that are identified through the annual determination process specified in the rule to take observers upon NMFS' request. The purpose of this measure is to learn more about sea turtle interactions with fishing operations, to evaluate existing measures to reduce sea turtle takes, and to determine whether additional measures to address prohibited sea turtle takes may be necessary. NMFS and/or interested cooperating entities will pay the direct costs of the observer. Through this rule, NMFS also extends the number of days from 30 to 180 (with a possible 60-day extension) that the agency may place observers in response to a determination by the Assistant Administrator that the unauthorized take of sea turtles may be likely to jeopardize their continued existence under existing regulations. This extension will help the agency address immediate observer needs in response to an emergency sea turtle-related event.