This rule extends the measures in an emergency interim final rule for the North Atlantic shortfin mako shark fishery published on March 2, 2018. This extension is necessary to maintain measures that address overfishing of shortfin mako sharks while long-term measures are developed and to meet requirements of a recommendation of the International Commission for the Conservation of Atlantic Tunas (ICCAT). The rule is expected to reduce fishing mortality to address overfishing, consistent with ICCAT Recommendation 17-08, by continuing to reduce landings and increase live releases in the recreational and commercial HMS fisheries, but is not expected to result in significant economic impacts.