SALMON AND TROUT IN ALASKA. 



81 



Differences in Averages of the Sexes. 

 [Except where the minus sign appears, the figures represent excess in average of the males.] 



Locality. 



Yes Bay. . 



Karta Bay 

 Quadra. . . 

 Kegan 



Locality. 



Nowiskay . . 



Dolomi 



Port Chester 

 Tamgas 



Depth. 



9.1 

 9.7 

 7.0 

 4.9 

 9.4 

 4.7 



It will be noted that this table shows a smaller average size for 

 the fish of 1904, except in one instance (Kegan); there the number 

 obtained in 1903 was too small for accurate comparison. 



The variation in depth between the two sexes seems to be prac- 

 tically constant, about 1 per cent of the measured length (which 

 measurement is about three-fourths of the total length), or less than 

 1 per cent of the total length. The dates at which the examinations 

 were made do not alter this ratio, showing that ordinarily there is 

 no great increase of the depth in the male while still in salt water, 

 and that variations of proportionate depth, as shown in the different 

 localities, are not an effect of secondary sex changes. In all instances 

 the males are heavier, although in a few cases slightly shorter than 

 the females. This difference in weight varies from 3.6 per cent in 

 the case of one lot of Quadra fish to over 15 per cent in the case 

 of the Nowiskay fish of 1904. The greater weight is attributable 

 to the greater depth of the males, which exceeds the depth of the 

 females by from 4 to over 7 per cent on the average. In these sex 

 variations there seems to be no marked similarity in the two seasons 

 for a given locality, the resemblance between different localities 

 being greater in some cases than between different years in the same 

 locality. In the few weights of Karta Bay fish taken in August, 1904, 

 the difference in average of the two sexes is remarkable, amoimting to 

 over 16 per cent. This is probably due to the increased weight of the 

 later rumiing males. In aU questions involving weight, analysis 

 should be made to see what increase is due to mere increase of 

 water in the tissues. 



The only spawned sockeyes weighed were at the Fortmann Hatchery. 

 These were apparently a somewhat different fish from those of other 

 localities, so no data as to the loss suffered during migration and 

 spawning could be deduced. Seventy-two males averaging 539 mm. 

 (std.) in length (480-605) averaged 7.4 pounds in weight, or con- 

 siderably heavier than fresh fish of the same length from other 

 localities. The combined average of green fish of similar lengths 



