The salmon runs of the Columbia River constitute one of the most important natural resources of the states of Oregon and Washington. Thousands of people are dependent, wholly or in part, upon these resources for their livelihood; and their welfare is dependent upon the maintenance of the salmon runs. It is to the special interest of these people that the salmon supply be maintained at the level of maximum productivity and, indirectly, it is to the interest of all the citizens of these states that this be done. In recent years it has become increasingly evident that these resources, taken as. a whole, are decreasing in productivity and it has been frequently pointed out that this decrease is due primarily to the operation of two factors-- a very intensive fishery and a reduction in spawning and rearing areas due to the utilization of the water resources of the Columbia basin for other purposes. These influences, however, have affected the several species of salmon that are found in the Columbia River quite differently; the more valuable species, Chinooks and bluebacks, showing more evidence of depletion than do the other species, silver salmon, chums and steelhead.