Gutierrez

BACKGROUND

At the heart of this case are chinook and coho salmon and steelhead trout populations from Puget Sound, lower Colum- bia River, and Snake River (collectively, “salmon”). Twenty- six populations of these salmon are listed as threatened or endangered under the Endangered Species Act, 16 U.S.C. 14326 SALMON SPAWNING & RECOVERY v. GUTIERREZ § 1531 et seq. (“ESA”). During their lifetime, these fish swim northward toward waters off the coast of British Columbia and Alaska, and then journey back through Alaskan and Canadian waters to return to their rivers of origin, where they spawn and die. Because of these unusual transboundary migration patterns, ESA-listed salmon that originate in United States waters are often caught by commercial and recreational fishers in Canada before they can make it back to their rivers of origin.

In 1985, Canada and the United States entered into the Pacific Salmon Treaty to manage salmon populations origi- nating in Alaska, Canada, and the Pacific Northwest. That version of the Treaty set harvest ceilings for fisheries in both countries. Those ceilings remained constant from year to year. The ceilings initially proved successful at…