130 U. S. BUREAU OF FISHERIES. 



of this theory stands the fact that no breeding ground of the red 

 salmon has vet been reported from any part of the Yukon Basin. 

 The breeding ground of this species could be looked for only in con- 

 nection with some lake, as the red salmon will not sj^aAvn under other 

 than lake conditions. And the males of the species, when on the 

 spawning grounds along the shores of a lake, or in the shallows of 

 the creeks which enter it, are of such brilliant color as invariably to 

 attract attention. It may be, therefore, that no permanent colony 

 of red salmon exists in the Yukon, and that the major portion of the 

 individuals observed off the mouth of the river would not enter and 

 ascend the stream. Occasional individuals do, however, ascend the 

 Yukon, for the writers learned of their infrequent occurrence from 

 observers acquainted with the different species of salmon, and one 

 specimen (a male, decidedly pink in color) was seen at Ruby on 

 August 14. During the much longer fishing season of 1919, 20 cases 

 of red salmon were packed by the cannery. 



HUMPBACK SALMON. 



The humpbacks appear at the mouth of the river more numerously 

 than the red salmon, but never in sufficient numbers to constitute a 

 run, even of small dimensions. It was noticeable that they were 

 far advanced toward spawning in July, often with liquid milt and 

 partly free eggs. It would be impossible for them to ascend the river 

 far with their spawning period so close at hand. In fact, there were 

 no reports of their occurrence above Andreafski, where a ripe male 

 was observed on August 3. 



COHO SALMON. 



The least in value of the three principal species is the coho, which 

 runs much less numerously than the other two, and, in addition, is 

 the latest to appear, often not presenting itself in any numbers in 

 the middle and upper reaches of the river until the ice is forming in 

 the fall. This species is little dried on account of its late appearance, 

 but may be fed fresh to the dogs or frozen for later consumption. It 

 seems liot to be highly valued for human food. 



During the season of 1920 it was entering the mouth of the river 

 in very limited numbers during the last week in July, but nothing 

 approximating a run had at that time developed. The individuals 

 then entering Avere bright silvery on the sides of the body, without 

 trace of the red coloration which later appears, and the jaws of the 

 male had developed no hook. Later, while inspecting the fishing 

 camps between the mouth of the river and Tanana, from August 2 

 to 15, everywhere occasional individuals of this species were being 

 taken. At Ruby on August 14 the fish wheels were catching from 

 one to six cohos each day; but at the Ramparts above Tanana on 

 August 20 the species had not yet put in an ai)pearance, nor could 

 anything be learned of its occurrence in the main river above Tanana 

 up to the date of the party's return from Dawson on 'September 5. 

 The individuals observed below Tanana were running j^rincipally 

 along the left (soutli) limit of the river, and it was reported that 

 their main run was always along the left bank in company with the 

 bright chums ("silver") and such king salmon as run late. To what 



