CHARACTERISTICS OF SPAWNING NESTS OF COLUMBIA RIVER SALMON 



103 



visible, that were deserted by salmon for no other 

 ascertainable reason than that there was little or 

 no flow of water through the gravel. Gravel 

 firmly cemented with silt and clay binders usually 

 lacked a percolating flow and was avoided by 

 Entiat River chinooks and by salmon in other 

 streams. All species showed a decided preference 

 for moderately bound stream-bed materials in 

 place of either loose shingle (free-rolling gravel) or 

 firmly bound rubble. 



Nearly all spawning of summer chinook salmon 

 in the White River took place in areas of the stream 

 that contained 95 percent medium and small 

 gravel. As shown in figure 5a, circle D, 9 redds 

 were measured and the average nest area was 4.7 

 square yards. Although this appears to contradict 

 the inverse-ratio relation between gravel size and 

 redd area, it is not considered significant, in view 

 of the small number of redds measured. As its 

 name implies, the White River is clouded by quan- 

 tities of chalky glacial material during the summer 

 and fall run-off, and this made observations diffi- 

 cult. 



The redds studied in the Entiat, Wenatchee, and 

 White Rivers were made by salmon transplanted 

 to each spawning area over a long period of time. 

 Relocation was spaced out in order to keep the 

 sexes evenly distributed in each area. As a result, 

 there was a mixture of stocks, or races, of summer 

 chinook on the same spawning areas, and a wide 

 assortment of sizes of redds resulted. Although the 

 summer chinook are a little larger, as a class, than 

 the fall chinook, their redds contained about the 

 same proportion of large, medium, and small 

 gravel as fall-chinook redds. Figure 5a, circle E, 

 shows that average redd size and gravel composi- 

 tion, for summer chinook in the Wenatchee River 

 are comparable to the redd sizes and gravel com- 

 positions for fall chinook in the Toutle River sys- 

 tem, figure 5o, circles G and H. 



FALL CHINOOK 



The Kalama River, the Toutle River, and the 

 Green River tributary of the Toutle, were selected 

 for study of fall chinook salmon redds. The 

 Toutle River is a tributary of the lower Columbia 

 through the Cowlitz River; the Cowlitz and the 

 Kalama enter the Columbia only a few miles 

 apart, about 60 miles from the sea. Thus, they 

 are neighboring streams and they have somewhat 

 similar watersheds — both are moderately forested 



and have fair gradients — but here the resemblance 

 ends. Because of an insurmountable falls, the 

 Kalama River has only 7 miles of available spawn- 

 ing area, containing a high proportion of large 

 gravel. Most of the stream bed is of stratified 

 gravel, that is, stream-bed disturbances and sub- 

 sequent flooding have overlaid the large gravel 

 with successive layers of smaller stones. During 

 redd digging the salmon encountered the sub- 

 stratum of large rocks with the result that the 

 redds resemble oversize underwater Easter egg 

 baskets. The Kalama River fall-chinook redds 

 contained a higher proportion of large gravel 

 than did other fall-chinook redds. (See fig. 5a, 

 circle F.) 



The Toutle River and its Green River tributary 

 are both accessible through virtually all their 

 lengths, presenting 40 miles or more of stream bed 

 with a greater choice of spawning rubble than is 

 available to the Kalama River fall chinooks. 

 The areas used contained gravel of relatively 

 uniform size with little or no stratification. 

 Whereas the Kalama River redds averaged 5.7 

 square yards with 41 percent large gravel, the 

 Toutle River redds averaged 6.5 square yards 

 with 11 percent large gravel. 



It would appear, from examination of figure 

 5a, circles F, G, and H, and figure 6, that the 

 abundance of large gravel in the Kalama had the 

 effect of reducing the size of the fall-chinook redds 

 there as compared with fall-chinook redds in the 

 Toutle River and its Green River tributary. 

 The slightly smaller average for the size of the 

 Green River redds, figure 5a, circle G, may be 

 attributable to the fact that fewer redds were 

 measured; figure 6 shows that the modal size of 

 the Green River redds is greater than that of the 

 Kalama River redds. These differences might be 

 explained on the basis of the mechanics of redd 

 building: the large gravel in the Kalama was 

 difficult to dislodge and to move, so the resulting 

 redds were smaller, whereas the medium gravel of 

 the Toutle River was easier to dig in and produced 

 larger redds. 



SILVER SALMON 



Silver salmon are distributed throughout the 

 North Pacific from mid-California to Alaska and 

 in Asiatic waters as far south as Japan. The 

 greatest runs are found in the streams of Oregon, 

 Washington, British Columbia, and southeastern 



