154 LOWER VERTEBRATES. 



dinate runs varying with each different river. In general, the runs are slack in the 

 summer and increase with the first high water of autumn. By the last of August 

 only straggling blue-backs can be found in the lower course of any stream, but both 

 in the Columbia and the Sacramento the quinnat runs in considerable numbers till 

 October at least. In the Sacramento the run is greatest in the fall, and more run in 

 the summer than in spring. In the Sacramento and the smaller rivers southward, 

 there is a winter run, beginning in December. The spring salmon ascend only those 

 rivers which are fed by the melting snows from the mountains, and which have suffi- 

 cient volume to send their waters well out to sea. 



Those salmon which run in the spring are chiefly adults (suj)posed to be at least 

 three years old). Their milt and spawn are no more developed than at the same time 

 in others of the same species which will not enter the rivers until fall. It w^ould 

 appear that the contact with cold fresh water, when in the ocean, in some way cause 

 them tq, turn toward it and to ' run ' before there is any special influence to that end 

 exerted by the development of the organs of generation. 



High water on any of these rivers in the spring is always followed by an increased 

 run of salmon. The canners think, and this is probably true, that salmon which would 

 not have run till later are brought up by the contact with the cold water. The cause 

 of this effect of cold fresh water is not understood. We may call it an instinct of the 

 salmon, which is another way of expressing our ignorance. In general, it seems to be 

 true that in those rivers and during those years when the spring run is greatest, the 

 fall run is least to be depended on. 



As the season advances, smaller and younger salmon of these two species (quinnat 

 and blue-back) enter the rivers to spawn, and in the fall these young specimens are very 

 numerous. We have thus far failed to notice any gradations in size or aj)pearance of 

 these young fish by which their ages could be ascertained. It is, however, probable 

 that some of both sexes reproduce at the age of one year. In Frazer River, in the 

 fall, quinnat male grilse of every size, from eighti inches upwards, were running, the 

 milt fully developed, but usually not showing the hooked jaws and dark colors of 

 the older males. Females less than eighteen inches in length were rare. All, large 

 and small, then in the river, of either sex, had the ovaries or milt well developed. 



Little blue-backs of every size down to six inches are also found in the upper 

 Columbia in the fall, with their organs of generation fully developed. Nineteen 

 twentieths of those young- fish are males, and some of them have the hooked jaws and 

 red color of the old males. 



The average weight of the quinnat in the Columbia, in the spring, is twenty-two 

 pounds ; in the Sacramento about sixteen. Individuals weighing from forty to sixty 

 pounds are frequently found in both rivers, and some as high as eighty pounds are 

 reported. It is questioned whether these large fishes are those which, of the same 

 age, have grown more rapidly; those which are older, but have, for some reason, failed 

 to spawn; or tliose which have survived one or more spawning seasons. All of these 

 origins may be possible in individual cases ; we are, however, of the opinion that the 

 majority of these large fish are those which have hitherto run in the fall, and so may 

 have survived the spawning season previous. 



Those fish which enter the rivers in the spring continue their ascent until death 

 or the spawning season overtakes them. Probably none of them ever return to the 

 ocean, and a lai-ge proportion fail to spawn. They are known to ascend the Sacra- 

 mento to its extreme head-waters, about four hundred miles. In the Columbia they 



