50 U. S. BUREAU OF FISHERIES 



were sexually immature while only 45 per cent Avere mature. This 

 was the case in spite of the fact that none of the fish were below the 

 legal weight limit (l^^ pounds in the round). 



There is some evidence, however, that the commercial catches of 

 the fall are differently constituted, being composed almost entirely 

 of breeding fish and presumably, therefore, of larger and older indi- 

 viduals. To obtain additional material from these spawning schopls 

 some time was spent in the field at Alpena. These data are now being 

 studied. 



In addition to the whitefish study the herring run in the fall of 

 1924 in Saginaw Bay was investigated. Abundant scale material and 

 other data were collected each day during the entire herring run 

 until ice conditions made fishing impossible, but they have not yet 

 been carefully analyzed. 



PACIFIC COAST AND ALASKA 

 ALASKA SALMON 



As before, these investigations have been conducted under the 

 direction of Dr. C. H. Gilbert, of Stanford University. The summer 

 of 1924 was spent principally in investigating the run of red salmon 

 to the Karluk River on Kodiak Island. Enough specimens were 

 taken at random from the daily catch to afford a fair sample, and by 

 means of their scale structure these were classified with respect to 

 their total age and as to the length of their early sojourn as finger- 

 lings in fresh water. 



The Karluk has been selected as a favorable stream in which to 

 investigate the efficiencj^ of natural propagation and in particular 

 what constitutes a reasonable expectation for future runs based on a 

 known volume of spawning fish. In order to ascertain the number of 

 spawners the bureau has each year since 1921 maintained a weir or 

 rack constructed entirely across the Karluk River, near its 'mouth, and 

 provided with a number of narrow openings through which the 

 ascending fish must pass and where they can be enumerated. 



The size of the runs in successive years has varied widely and the 

 escapement tallied through the weir has varied proportionately from 

 about 1,330,000 spawners in 1921 to approximately 300,000 in 1922. 

 Such widely differing brood years should pi'oduce equally differing 

 results wlien their progeny reach maturity, unless other factors inter- 

 fere. This is a matter that has never iDeen investigated, and it is 

 hoped to secure results of scientific and practical value from the 

 Karluk experiment. 



It is the bureau's plan to ascertain the total returns from the 

 various spawnings by enumerating the progeny of each year when 

 they return as mature fish. This could be easily accomplished if all 

 individuals matured at the same age, but this is far from the case. 

 In the Karluk race, as we ascertained during the season of 1924, 

 some individuals mature in their third year while others mature in 

 the fourth, fifth, sixth, or seventh year". The progeny of the 1921 

 spawning are therefore to be looked for in the runs of a number of 

 successive years. Th- 3-year-olds would make their appearance in 

 1924, the 4-year fish in 1925, and so on until 1928, when the last of 



