Bycatch is the principal and most immediate threat to many species and populations of marine mammals. In many parts of the world, especially in countries with large artisanal fishing sectors, the extent of this bycatch is largely undocumented. This project will take the initial step of understanding the bycatch associated with particular fisheries—industrial and small-scale—in Ecuador, Chile, and Thailand, so that bycatch reduction programs can be directed at the fisheries where they are most needed.