U.S.-Canadian management of marine migratory species is a particularly rich place to understand the complex relationship between migratory science, conservation, and law. The two nations share a large border, have a long-lasting historic friendship, and already collaborate extensively. However, the relationship is not without contention. The substantial economic interests in the oceans and differences in governance structure have not infrequently frustrated efforts at cooperative management. And even when the two countries endeavor to work closely together, they face daunting management and coordination challenges: the fate of the critically endangered North Atlantic right whale—whose numbers now hover at only 70 reproductive females—exemplifies the problem. To explore ways to improve this bilateral relationship and further protect marine migratory species, the Duke University School of Law, the Environmental Law Institute, and both the Marine & Environmental Law Institute and the Ocean Frontier Institute at Dalhousie University in Halifax, Nova Scotia, hosted a workshop in Washington, D.C., in late 2022 that brought together participants from numerous agencies and academic institutions, including the Department of Fisheries and Oceans Canada, Parks Canada, and the U.S. National Oceanic and Atmospheric Administration. This Comment summarizes the workshop findings, and builds on the separately published workshop proceedings to recommend actions for U.S. lawmakers and regulators to improve the management of migratory marine species that inhabit both U.S. and Canadian waters.