On June 30, 1999, U.S. and Canadian officials signed a new comprehensive agreement to resolve long-standing disputes and to ensure implementation of the conservation and harvest-sharing principles of the 1985 Pacific Salmon Treaty (PST). After years of failed negotiations, a combination of resource management studies, joint-fishery restrictions to protect wild salmon stocks, and the involvement of high-level government negotiators helped ease tensions between the United States and Canada over the shared harvest of Pacific salmon. Moreover, the two nations recognized that failure to reach a long-term conservation and harvest-sharing agreement was in no one's best interest. The provisions in this agreement's Annex IV outline, in detail, the fishery regimes to be followed by Canada and the United States in cooperatively managing the five species of Pacific salmon. Most chapters of Annex IV expired at the end of 2008, and discussions began in 2005 on its renegotiation. This report provides historical background about the PST, discusses issues that created difficulties in the regime, summarizes the 1999 salmon accord, and outlines issues relevant to the renegotiation of Annex IV. The 1999 Agreement (1) established abundance-based fishing regimes for the Pacific salmon fisheries under the jurisdiction of the PST; (2) created two bilaterally managed regional restoration and enhancement endowment funds to promote cooperation, improve fishery management, and aid stock and habitat enhancement efforts; and (3) included provisions to enhance bilateral cooperation, improve the scientific basis for salmon management, and apply institutional changes to the Pacific Salmon Commission (PSC). Pacific salmon have long been a matter of common concern to the United States and Canada. In the 1800s, with the advent of canning technologies, extensive commercial salmon fisheries developed in both countries. Since their inception, salmon fisheries have experienced strong fluctuations in catch and stock abundance. Periods of great plenty were often followed by years of low returns. By the 20 th century, it had become obvious that the combined effects of fishing and natural variability in abundance could lead to overharvest. The United States and Canada recognized that some form of cooperation would be necessary for the sake of the resource. For many years, piecemeal agreements were forged to protect specific fisheries, such as Fraser River sockeye and pink salmon. However, because of the diversity in salmon fisheries and recurring disagreements over how best to address the interception problem, these agreements proved inadequate. In 1985, the PST created an arrangement for cooperative management, research, and enhancement of all intercepted Pacific salmon stocks. The goal of the PST is coordinated management of Pacific salmon throughout their range to ensure sustainable fisheries and maximize long-term benefits to the parties. Despite the PST, some salmon stocks continued to decline. Interceptions strained diplomatic relations between the United States and Canada, and the parties fundamentally disagreed on how to achieve the conservation and harvest-sharing goals established by the PST. After a long-term harvest agreement expired in 1992, Canada argued strongly that the United States was exceeding its share of the catch under the PST's "benefits equivalent" provisions. In contrast, the United States argued that Canadian interceptions of Pacific Northwest (Washington, Oregon, and Idaho) coho salmon and Chinook salmon were further damaging these depleted stocks. In years following 1992, a unstated assumption of both parties—that they would both abide by conservation measures—allowed the two countries to manage their fisheries. In 1997, bilateral stakeholder talks were held in an attempt to resolve the impasse. Ultimately, these negotiations failed to forge an agreement. In August 1997, the United States and Canada appointed William Ruckelshaus and David Strangway, respectively, to conduct a joint investigation and to make recommendations for ending the controversy. In addition, Washington State and Canada agreed to restrict several of their fisheries to help protect wild salmon stocks. However, failure to reach a long-term conservation and harvest-sharing agreement harmed several salmon stocks and hampered the ability of Washington, Alaska, and British Columbia fishermen to plan fishing seasons and budget expenses because, without a harvest-sharing agreement, year-to-year salmon allocations were unpredictable. Thus, the 1999 Agreement represented a major breakthrough in a longstanding contentious resource issue. Pacific salmon are among the world's most highly migratory anadromous fish. They spawn in fresh water, often hundreds of miles from the ocean, migrate to the sea as juveniles, and then disperse into the open ocean. From one to several years later, they return to their natal rivers to spawn and complete their life cycle. Along the Pacific Coast of North America, many juvenile salmon travel north after they enter the ocean, migrating freely across the national boundaries of the United States and Canada and into international waters (see Figure 1 ). There are six species of anadromous Pacific salmon and trout: Chinook (king) salmon ( Oncorhynchus tshawytscha ), sockeye (red) salmon ( O. nerka ), coho (silver) salmon ( O. kisutch ), pink (humpy) salmon ( O. gorbuscha ), chum (dog) salmon ( O. keta ), and steelhead trout ( O. mykiss ). Migration patterns widely vary among the species. Because of their value and importance to U.S. and Canadian fisheries, three species—Chinook, sockeye, and coho—are of particular interest. Chinook salmon from central and northern Oregon coastal rivers, the Columbia River system, and drainages entering Puget Sound generally swim north as juveniles, some migrating as far as the waters off northern British Columbia and Alaska. Coho salmon stocks generally do not migrate as far north and the southern coho stocks (fish originating in Washington/Oregon and southern British Columbia) generally do not mingle with the northern stocks (originating in northern British Columbia and Alaska), which frequently migrate through the waters off southeast Alaska. Because of this natural segregation, the northern and southern coho stocks are addressed separately in the PST. Sockeye salmon from British Columbia's Fraser River move in different patterns depending on ocean conditions. In years when El Niño climatic events occur, Fraser River sockeye are more prevalent in southeast Alaskan waters, returning to the Fraser River through Johnstone Strait off the west coast of the British Columbia mainland. In other (non- El Niño ) years, Fraser River sockeye exhibit a somewhat more southerly distribution and return through the Strait of Juan de Fuca. As a result of these migration patterns, fishermen in the United States and Canada intercept fish originating in and returning to rivers of the other country, often in substantial numbers. Canadian commercial troll fisheries off the west coast of Vancouver Island (WCVI) often catch Chinook and coho salmon bound for the rivers of Oregon and Washington, including some threatened and endangered stocks. WCVI trollers and recreational anglers also harvest Puget Sound Chinook. Fishermen in southeast Alaska catch salmon returning to rivers in Canada and the Pacific Northwest. In some years, Washington State commercial fisheries, both tribal and non-tribal, may catch large numbers of Fraser River sockeye as they migrate through the Strait of Juan de Fuca. For many years, these interceptions caused tension between the United States and Canada. Thus, salmon migration patterns and interceptions complicate negotiations. A 1937 arrangement between the United States and Canada to conserve and equitably divide the harvest of Fraser River sockeye salmon was an early success story in the management of shared salmon stocks. The Fraser River lies wholly within Canada, but sockeye salmon generally pass through U.S. waters as they return to spawn. Thus, Fraser River sockeye supported large fisheries in both the United States and Canada, setting the stage for an international drama. In the late 1800s, Canadian fishermen dominated the Fraser River sockeye fishery. By 1900, with the expansion of U.S. purse seine fisheries, U.S. harvest quickly surpassed the Canadian harvest. From 1900 through 1934, U.S. fisheries produced from 61% to 70% of the sockeye salmon canned from the Fraser River run. In 1913, crews blasting a railroad right-of-way through the canyon walls above the Fraser River triggered a massive rock slide that choked the river canyon. The effects of the slide were most detrimental at a narrow section of the river known as Hell's Gate, blocking access to spawning areas upstream from the slide. United States and Canadian harvest of sockeye salmon dropped dramatically. By 1918, with substantial U.S. assistance, the Hell's Gate reach was restored, and sockeye salmon could again move upstream to spawn. The rise of competing U.S. and Canadian fisheries, natural fluctuations in salmon stock abundance, and the events at Hell's Gate provided impetus for negotiations between the United States and Canada over the cooperative management of the sockeye salmon stocks. In 1937, after seven years of negotiation, the Fraser River Convention was ratified. The Convention established the International Pacific Salmon Fisheries Commission, with principal responsibility for protecting, preserving, and extending the sockeye salmon fisheries of the Fraser River (pink salmon were later added to the Convention). The commission operated under two objectives: (1) restore Fraser River sockeye runs; and (2) equally divide the catch, within practical limits, between U.S. and Canadian fishermen. In 1946, the commission recommended that regulations be implemented to: provide closures designed to permit adequate escapement of all races of salmon comprising the run; protect in the greatest possible degree the most seriously depleted runs; divide the total catch as equally as might be possible between the fishermen of the two countries; and permit the largest catch possible consistent with attainment of these objectives.