Once Columbia River Basin salmon and steelhead reach the Pacific, they face a diminished chance of being harvested simply because there are fewer fishers in the vast ocean than in the narrow confines of the river. However, fewer harvesters hasn’t always meant lower impacts.

Ocean fishing fleets, particularly from Japan and Taiwan, once ruthlessly swept the north Pacific with nylon-filament nets up to 100 miles long in some cases. Seabirds, marine mammals and all kinds of fish, including salmon and steelhead, were captured and killed in these indiscriminate, unregulated fisheries.

To effect some regulation and establish boundaries for ocean fishing, in 1952 Congress adopted the International Convention for the High Seas Fisheries of the North Pacific Ocean. Known as the Trilateral Pacific Salmon Treaty, the agreement between Japan, the United States and Canada embodied the “abstention principle.” Abstention means that the nation where anadromous fish originate has authority to prohibit high seas fishing on those stocks. Accordingly, Japan was were prohibited from fishing on Canadian or United States salmon east of a line drawn roughly along the 175th meridian, which is roughly in the middle of the ocean.

The 1952 treaty also established the International North Pacific Fisheries Commission to conduct research into the life histories of North Pacific salmon stocks, which were virtually unknown in 1952. The Fishery Conservation Management Act of 1976 (The Magnuson Act) asserted United States control of anadromous fish of United States origin beyond a 200-mile limit, effectively rendering the 1952 treaty obsolete.

The Trilateral Pacific Salmon Treaty was renegotiated in 1978, again between Japan, Canada and the United States. Provisions were substantially the same, except that the “abstention” line was moved 10 degrees of longitude to the west, across the international date line in order to further reduce Japanese harvest of U.S. and Canadian salmon.