SARLUK RIVER RED-SALMON INVESTIGATION 



35 



As we have previously stated, the Karluk grilse have little commercial value. 

 Their flesh is conspicuously deficient in color and oil and their size is so small they 

 can not be handled economically. As they are so largely males, they could have 

 biological significance, it would seem, only in case there were a marked deficiency 

 of males among the older fish that make up the main body of the run. A deficiency 

 of males does exist, in fact, and this appears to be a constant feature of the Karluk 

 race. Excluding from consideration the grilse, our random sampling of adults 

 throughout the season of 1924 (4,776 individuals) gave 46 per cent males and 54 per 

 cent females. In 1925, with 5,214 individuals, there were 44 per cent males and 56 

 per cent females. In 1926, with 8,114 individuals, there were 43 per cent males and 

 57 per cent females. This is an unusual condition among red-salmon races and 

 appears the more remarkable from the fact that, aside from the grilse, every important 

 year class shows a deficiency of males. Whether in natural spawning, with a defi- 

 ciency of males, a single male will serve more than one female is a question to which 

 we have no answer as yet. If they will not do so, the unusual development of grilse 

 in the Karluk race may have a useful purpose. 



To recapitulate: No. 1 grilse spend a single summer in sea feeding, are exclu- 

 sively males, and become mature near the close of the same season in which they 

 migrate seaward from the lake. They are drawn almost exclusively from migrating 

 fingerlings in their fourth and fifth years. The much larger group of 3-year finger- 

 lings contributes very few individuals that mature during their first summer in the sea. 



No. 2 grilse mature during their second summer in the sea and in greatest numbers 

 toward the close of the summer, when females appear in limited numbers with the 

 greatly preponderating males. 



The great majority of the Karluk red salmon, those that constitute the back- 

 bone of the run, mature during their third summer in the sea, when they are in their 

 fifth or sixth year. Of these two, the 5-year class is by far the most important, for 

 it develops from the 3-year fingerlings, which constitute the great majority of the 

 downstream migrants. The 4-year fingerlings also develop principally during their 

 third summer at sea and form the sixth year class above mentioned. It constitutes 

 the second most important group in the run. In 1926, the 5-year class here consid- 

 ered comprised about 80 per cent of the run and the 6-year class about 10 per cent. 



We can state, therefore, that despite the very wide diversity in life history found 

 among the Karluk red salmon, there is one prevailing mode to which the majority 

 conform. These migrate seaward as fingerlings in their third year and mature in 

 their fifth year, during their third summer at sea. In case the fingerlings have 

 lingered one year longer in fresh water, they still largely conform to the racial habit 

 of maturing in their third sea summer and are then in their sixth year. 



ANALYSES OF RECENT RUNS 



As previously stated, the primary object of our investigation is to ascertain 

 the natural yield from a spawning colony of known size — to determine the ratio 

 between the number of parents spawning in any given year and the number of the 

 resulting progeny, when the latter shall return at maturity. Will a single pair of 

 spawners produce, on the average, 1 pair of mature salmon, or 2 pairs, or 5 pairs, or 

 10 pairs? 



