The Chinook Salmon 



day. As they go farther and farther up-stream they swim rather 

 more rapidly. Tiiose that enter tiie river first are the ones 

 wliich will go farthest toward the head waters, many of them 

 going to spawning beds in Salmon River in the Sawtooth 

 Mountains of Idaho, more than i,ooo miles from the sea. Those 

 which enter the river later travel more rapidly, but do not go 

 so far toward the headwaters, while those last to pass by Astoria 

 have so long delayed the movement that they are nearly ready 

 to spawn and, consequently, must travel rapidly and enter the 

 first small tributary streams which they reach. Those which go to 

 the headwaters of the Snake River in the Sawtooth Mountains 

 spawn in August and early September; those going to the Big 

 Sandy in Oregon, in July and early August; those going up 

 Snake River to upper Salmon Falls, in October; while those 

 entering the small lower tributaries of the Columbia or the small 

 coastal streams spawn even as late as December. Observations 

 which we have made at various places indicate that wherever 

 the spawning beds may be, spawning will not begin until the 

 temperature of the water has fallen to 54° Fahr. If the fish 

 reach the spawning grounds when the temperature is above 54°, 

 they wait until the water cools down to the required degree. 



It has been often stated and generally believed that the sal- 

 mon receive many injuries by striking against rocks and in other 

 ways while en route to their spawning grounds and, as a result 

 from these injuries, those which go long distances from the sea 

 die after once spawning. An examination of many salmon at 

 the time of arrival on their spawning beds in central Idaho 

 showed every fish to be entirely without mutilations of any kind, 

 and apparently in excellent condition. Mutilations, however, soon 

 appeared, resulting from abrasions received on the spawning 

 beds while pushing the gravel about or rubbing against it, and 

 from fighting with each other, which is sometimes quite severe. 



The spawning act extends over several days, the eggs being 

 deposited upon beds of fine gravel in clear, cold mountain 

 streams. Soon after they have done spawning both males and 

 females die, each individual spawning only once. This is true of 

 all, whether spawning remote from salt water or onlv a few 

 miles or yards from the sea. The cause of their dying is not 

 conditioned upon distance from the sea, but is general in its 

 application to all species of Pacific Coast salmon. 



152 



