Atlantic Highly Migratory Species fisheries are managed under the dual authority of the Magnuson-Stevens Conservation and Management Act (Magnuson-Stevens Act) and the Atlantic Tunas Convention Act, which implements U.S. obligations as member of the International Commission for the Conservation of Atlantic Tunas. North Atlantic shortfin mako sharks were recently determined to be overfished and experiencing overfishing, and the Commission's member countries, including the United States, adopted management measures in 2017 to take immediate action to reduce fishing mortality of the stock, including releasing of live sharks and increasing minimum sizes. This proposed action for shortfin mako sharks would implement the United States' obligations under those management measures to help prevent overfishing of the U.S. component of that stock and establish a foundation for a rebuilding program. Through the rulemaking process, NMFS would amend the 2006 Consolidated Highly Migratory Species Fishery Management Plan and examine management alternatives to address overfishing and establish a foundation for a rebuilding plan. This rulemaking would likely impact recreational and commercial fishing vessels that interact with shortfin mako sharks.