FISHERY BULLETIN: VOL. 70, NO. 1 



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_1 



SWftNSON RIVER, ftLASKA 



BEAR CREEK. ALASKA 



DAIRY CREEK .ALASKA 



KARLUK RIVER, ALASKA 



PASA6SMAK RIVER, ALASKA 



PORT HERBERT, ALASKA 



SASHIN CREEK, ALASKA 



KAMCHATKA RIVER, USSR 



USHKI HATCHERY, USSR 



NAMU RIVER. BRITISH COLUMBIA 



ERASER RIVER, BRITISH COLUMBIA 



PARATUNKA RIVER. USSR 



BOLSHAYA RIVER. USSR 



TYMI RIVER, USSR 



CULTUS LAKE, BRITISH COLUMBIA 



NILE CREEK. BRITISH COLUMBIA 



PORT JOHN. BRITISH COLUMBIA 



OLIVER CREEK, BRITISH COLUMBIA 



COWICHAN CREEK, BRITISH COLUMBIA 



BEADNELL CREEK, BRITISH COLUMBIA 



MINTER CREEK, WASHINGTON 



SEATTLE, WASHINGTON 



ALSEA RIVER, WASHINGTON 



SCOTT CREEK, CALIFORNIA 



_1_ 



_1_ 



1,000 



2,000 3,000 4,000 



NUMBER OF EGGS 



5,000 6,000 



Figure 3. — Average fecundity of various stocks of echo 

 salmon from North America and Asia. 



fork length by the method of least squares. 

 The result may be expressed by the equation 

 y = —7,503.55 + 195.51X, where Y is the esti- 

 mate of number of eggs and X is the mideye- 

 fork length of female salmon (Figure 4). The 

 mean number of eggs for the sample was 4,706 

 (range 1,724 to 6,906); the mean length was 

 62.1 cm (range 46.6 to 69.8 cm). 



2 3,000 



Figure 4. — Relation of fecundity to length of coho salmon 

 sampled at Karluk v^reir, 1966. 



FECUNDITY AS A FUNCTION 

 OF LENGTH 



The presence of a positive relation between 

 fecundity and length in the genus Oncorhynchus 

 is well known (Gilbert and Rich, 1927; Foerster 

 and Pritchard, 1941; Allen, 1958; Hartman and 

 Conkle, 1960). For fish in general, the relation 

 of fecundity to length is logarithmic (Y = aX^) 

 over a wide range of lengths. For salmon, how- 

 ever, the narrow range in length at maturity 

 permits this relation to be described adequately 

 by a straight line of the foi'm Y = a + bX (Foer- 

 ster and Pritchard, 1941; Rounsefell, 1957). 



I counted the total number of eggs in 49 coho 

 salmon from the Karluk River and calculated 

 the relation between number of eggs and mideye- 



It is difficult to determine if the high fecun- 

 dity of coho salmon of the Karluk system (Fig- 

 ure 3) is due to greater fecundity per unit length 

 or simply to the fact that coho salmon from Kar- 

 luk are very large. The average lengths of fe- 

 male coho salmon from various spawning 

 streams along the Pacific coast of North Amer- 

 ica are quite variable and do not seem to follow 

 any set geographic pattern (Table 3). More- 

 over, Karluk fish were measured from mideye 

 to fork of tail, and direct comparisons of lengths 

 with coho salmon from other areas are difficult 

 to make because of variability in the types of 

 measurements used. For instance lengths re- 

 ported from areas other than Karluk include 

 tip of snout to fork of tail (fork length), tip of 

 snout to tip of tail (total length), and tip of 

 snout to base of tail (standard length). 



84 



