FEMALE SALMON (0. verka) OF THE COLUMBIA RIVER 



437 



Tiiroc iiictliods were used to estimate tlie egg 

 poteiilial of 19"):^ iiiid 195() throiiiih in')9 ()k;uio<;aii 

 River escapements. The first metiiod was based 

 on the assumptions tliat one-half of the estimated 

 spawners were femah'S and tiiat tlie average egg 

 content per female was 3,000 eggs. Method 2 

 iiad as its base the observed number of female 

 spawners antj an average fecundity of li, ()()(), 

 The third and most refined metiiod was based 

 on th(> number of females in each age group and 

 tlu- average fccimdity of eacli age group. 



Comparison of the results of the tiuee methods 

 siiows that failure to correct for sex ratio and 

 fecundity when estimating the reproductive ca[)ac- 

 ity of an escapement can seriously distort llic 

 iiccuraey of the escapenuMit statistic for use in 

 escapement-return analyses. 



The high incidence of small females in tlie 

 1953 Rock Island escapement substantially re- 

 duced the egg potential normally expected of an 

 escapement of that size. This distortion of the 

 escapement statistic accentuated the poor escape- 

 ment-retuin relationship of 1953-57. 



LITERATURE CITED 



Fi.sH, Frederic F., and Mitchell G. Hanavan. 



1948. A report from the Grand Coulee fish-mainte- 

 nance project 1939-1947. U.S. Department of 

 Interior, Fish and Wildlife Service, Special Scientific 

 Report Xo. 55. 63 p. 

 Gancmark, Harold A., and Leo.nard \. Fulto.n. 



1952. Status of Columbia River blueback runs, 1951. 

 U.S. Department of Interior, Fish and Wildlife 

 Service, Special Scientific Report — Fisherie.s Xo. 

 74. 29 p. 

 Gilbert, Charles II., and Willis H. Rich. 



1927. Investigations concerning the red-salmon runs 

 to the Karluk River, Alaska. U.S. Bureau of 

 Fisheries, Bulletin, vol. 43, Part 2, p. 1-69. 

 Godfrey, Harold. 



1958. .A comparison of sockeye salmon catches at 

 Rivers Inlet and Skeena River, B.C., with particular 

 reference to age at maturity. Journal Fisheries 

 Research Board of Canada, vol. 15, No. 3, p. 331- 

 354. 



Xelson, Philip R. 



1959. Kffects of fertilizing Bare Lake, Alaska, on 

 growth and production of red salmon (0. nerka). 

 U.S. Fish and Wildlife Service, Fishery Bulletin, 

 vol. 60, Xo. 159, p. 59-86. 



Washington (State) Department of Fisheries. 



1959. 69th Annual Report, Year 1959. 243 p. 

 Seattle. 



U. S. GOVERNMENT PRINTING OFFICE : 1962 O -619361 



