30 



BULLETIN OF THE BUREAU OF FISHERIES 



during the season of 1926. This would represent over 3,000,000,000 eggs. Many 

 of the females, however, died after entering the lake but before spawning, and many 

 others died before depositing all of their eggs. It seems safe to say, however, that 

 well over 1,000,000,000 eggs were deposited in the gravels of the lake and of the 

 streams tributary to the lake. Of this tremendous number comparatively few sur- 

 vive even to make the seaward migration. The fate of those that do not survive, 

 and the factors that affect, favorably or otherwise, the survival of the eggs and young 

 fish during their life in fresh water,' are questions that can not be answered now 

 and are to be considered in the future study of the Karluk salmon. 



The period of the hatching of the eggs and the time of emergence of the fry 

 from the gravels is another subject that awaits investigation in the Karluk. That 

 these are virtually controlled by the temperature of the water is well known; and 

 from such data as we possess it is considered highly probable that the first fry to 

 emerge make their appearance not earlier than the following spring and consist 

 largely of those that, as eggs, were deposited earliest in the preceding summer. 

 Following these there may well be a continuous emergence of fry during all the 

 summer months, maintaining an order in their appearance corresponding roughly 

 with that in which the eggs were laid down during the previous season. It has been 

 observed elsewhere in western Alaska that fry of the previous season's spawning, 

 with yolk sac still attached, could be found at the very end of the season. These 

 were doubtless derived from the latest eggs to be laid the preceding fall. 



The young remain in Karluk Lake for a comparatively long period and during 

 this time make a sturdy growth. So far as known to us, none leave the lake on their 

 seaward migration before the spring of their second year, and even these are few in 

 number and form a negligible proportion of any brood. The great majority pass 

 down the river and out to sea in the spring of their third year, while a smaller number 

 remains in the lake until the spring of their fourth year, and an occasional individual 

 until the spring of its fifth year. Random samples were collected in the spring of 

 1926 on five different days, extending from May 30 until June 12, comprising in all 

 619 individuals. Of these, 1.6 per cent were in their second year (see fig. 21), 74 per 

 cent in their third year (fig. 22), 24 per cent in their fourth year (fig. 23), and 0.4 

 per cent in their fifth year (fig. 24). The youngest group averaged 96 millimeters 

 in length, the 3-year group 135 millimeters, the 4-year group 144 millimeters, and 

 the 5-year group 169 millimeters long. Of the total number, 314 were males and 

 305 females. 



In addition to the classes above enumerated, which comprise the regular sea- 

 ward migration of fingerlings, there are found in the river in spring and early summer 

 a limited number of fry in their first year, which are believed to straggle out to sea 

 during the early part of the season. Apparently they are not moving downward 

 with the regular seaward migration of lake fish, but are observed even after the 

 fingerling migration is past, in the eddies along the banks of the river and among 

 the water weeds along the shore where the current is slack; but they seem to have 

 disappeared before midsummer, and have doubtless gone to sea. The origin of these 

 fry has not been traced, and it is not known positively that none of them have come 

 out of the lake at this early age; but as considerable numbers of adult salmon are 

 known to spawn in the river gravels below the lake it is considered probable that 



