Reprinted from Proceedings of the Sixth Pacific Science Congress, University of California Press, Berkeley, California, 1941.THE SALMON of the Columbia River have supported an intensive fishery for over seventy years but are now showing unmistakable signs of depletion, and various factors are contributing to the rapid progress of this condition. Five species of fish enter into the commercial fishery on the Columbia River itself. These are (1) the Chinook salmon (Oncorhynchus tschawytscha), (2) the blueback salmon (0. nerka), (3) the silver salmon (0. kisutch) , (4) the chum salmon (0. keta) and (5) the steelhead trout (Salmo gairdneri) . The Chinook is of far greater importance than all other species together and constitutes by weight approximately three-quarters of the total catch. In addition to the catch made in the river a large number of Columbia River salmon are taken in the ocean, especially by trolling, but to a small extent by purse seines. This oceanic catch is almost exclusively composed of Chinooks and silver salmon. The annual commercial value of the pack of salmon on the Columbia River has averaged about four and a half million dollars over the past thirty years. Thousands of people are directly dependent upon this industry for all or part of their income and other thousands benefit indirectly. It constitutes one of the major resources of the Pacific Northwest.