436 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



(Washington Department of Fisheries, 1959). 

 The cross that involved the 2-year-old male pro- 

 duced a significantly larger number (168) of 

 2-year-old fish than did the cross that involved 

 the 3-year-old male (79). 



Ricker ^ using Adams River, B.C. (Canada) 

 data, found that "observed differences between 

 broods, in age of males at maturit}' is strongly in- 

 fluenced by the age of their fathers." 



Certain evidence, on the other hand, seems to 

 minimize the role of genetics in the recurrence of 

 precocious blueback salmon: (1) the lack of a sig- 

 nificant correlation between the 1-year-ocean blue- 

 backs of year n and those of year n4-3; (2) the 

 scarcity of these small fish in the Wenatchee sys- 

 tem. In 1939-43, the years of the Grand Coulee 

 Relocation Program, blueback salmon were inter- 

 cepted at Rock Island Dam and transported to 

 Lakes Osoyoos and Wenatchee (Fish and Hana- 

 van, 1948). Although exact data are lacking, 

 generally as many small l-j^ear-ocean fish were 

 placed in the Wenatchee as in the Okanogan sys- 

 tem. Were the recurrence of 32's entirely genetic, 

 we could normally expect a continuation of the 

 strain in each system. The absence of 1-year- 

 ocean fish in the Wenatchee runs suggests that 

 the conditions in that sj'stem simply did not 

 lend themselves to the production of 1 -year-ocean 

 fish. This aspect of the problem is clouded, how- 

 ever, by the lack of knowledge concerning the 

 kokanee-blueback ' relationship. 



Another question concerned with the function 

 of the 32's as a safety-factor is that of the relative 

 survival of eggs and progeny resulting from small 

 females. The ability of the small females to bury 

 the eggs deep enough to protect them from 

 physical rigors is also subject to speculation. 



CONCLUSIONS 



Fenude Columbia River blueback salmon that 

 spawn after spending only one year in the ocean 

 contain rouglily one-third fewer eggs than normal 

 2-year-ocean fenuxles. 



s Ricker, W. E. Evidence for environmental and genetic influence on 

 certain characters wiiicti distinguish stoclts of the Pacific salmons and steel- 

 head trout. Fisheries Research Board of Canada, Nanaimo, B.C. Un- 

 published manuscript, law. 



' Individuals of the species that complete their entire life cycle in fresh 



Escapements to the Okanogan spawning tribu- 

 tary exhibit wide annual fluctuations in age and 

 sex composition. Abnormal numbers of 1-year- 

 ocean females can greatly reduce the egg potential 

 of a particular escapement and, in turn, distort 

 the escapement-return relationship involving that 

 brood. 



The unusually high incidence of 1-year-ocean 

 fish in tlie 1953 Okanogan escapement reduced 

 the egg potential to about one-half that expected 

 of an escapement similar in size but normal in 

 age and sex composition. It appears this initiid 

 overestimation of egg potential may have ac- 

 centuated the relatively poor riverwide escape- 

 ment-return relationship of 1953-57. 



Although the 1-year-ocean fish have a lower 

 fecundity and contribute little directly to the 

 commercial fishery as it is now conducted, they I 

 may, by virtue of their contribution to reproduc- 

 tion, have a positive value as a safety factor in 

 the escapement. 



Further assessment of the value of 1-year-ocean 

 fish requires more exact knowledge about (a) 

 the role of genetics in the recurience of the 

 32's, (b) the relative survival of eggs deposited 

 by large and small females, and (c) the relative 

 viability of progeny produced by 2-year-ocean 

 parents, 1-year-ocean parents, and combinations 

 of both. 



SUMMARY 



Altiiough 1-year-ocean fish are common in 

 the spawning escapements of the Columbia 

 River blueback salmon, tlieir contribution to the j 

 reproductive capacity of an escapement lias not 

 previously been assessed. 



The need for assessment became evident when 

 the 1953 Rock Island escapement, whicii contained 

 unprecedented numbers of l-year-ocean fish, failed 

 to produce a total run in 1957 that exceeded 

 itself. 



A fecundity study, conducted from 1957-59, 

 revealed tiiat the 1-year-ocean females contained 

 33, 26, and 32 percent fewer eggs than the 2- 

 year-ocean fisli in those years, respectively. The 

 pooled -means of numbers of eggs per female 

 were 2,014 for 1-year-ocean fisli and 2,897 for 

 2-year-ocean fisli. 



