108 "CT-S. BUREAU OF FISHERIES 



fresh water form the predominating age group, and comprise from 78 

 to 82 percent of the catch. Fish maturing in 4 years after having 

 spent 2 winters in fresh water, and those maturing at 6 years after 

 having spent 3 winters in fresh water form the other two important 

 age groups which appear in about equal numbers in the catch. 



During the field season of 1931 data were collected for the purpose 

 of showing whether or not the red salmon utilizing distinct spawning 

 areas of the Copper River developed physical characteristics by which 

 they could be identified. A comparison of such physical characters 

 as number of vertebra, number of fin rays, number of branchiostegal 

 rays, and number of gill rakers does not show them to differ statis- 

 tically on fish from three important spawning areas. A further study 

 of the scales of fish from these tributaries is expected to provide 

 indications of racial differences. 



A preliminary analysis of catch statistics of the Copper River indi- 

 cates depletion as the result of overfishing in the period of peak pro- 

 duction from 1915 to 1922, and the catch of recent years strongly 

 reflects the beneficial eft'ects of the regulations imposed in 1924 and 

 subsequent years. 



PINK-SALMON INVESTIGATION 



In order to provide protective regulations for the pink-salmon run 

 in any stream or locality it is imperative to know if the salmon 

 hatched in that stream or locality return to it as adults. This brings 

 up the problem of determining the degree of individuality maintained 

 by the pink-salmon populations in different streams. The conven- 

 tional manner of solving such problems has been to mark the salmon 

 fry as they leave the streams and then observe the adult run that 

 returns, for individuals bearing the marks. Two experiments of this 

 nature have been completed thus far in the pink-salmon investigation 

 by Dr. Fredrick A. Davidson — one at the Government hatchery on 

 the Duckabush River in Washington, and one in Snake Creek at 

 Olive Cove, Alaska. The pink-salmon fry were marked in both of 

 these experiments by means of clipping their dorsal and adipose fins. 

 Thirty-six thousand fry were marked at Duckabush in the spring of 

 1930, and 50,000 fry were marked at Olive Cove in the spring of 1931. 

 The results from these experiments indicate that the majority of the 

 fry originating in these streams return to them as adults. There 

 were a few marked adults found in the neighboring streams both at 

 Duckabush and at Olive Cove, but the degree of straying was 

 comparatively meager. 



There are over 500 streams in southeastern Alaska in which pink 

 salmon spawn by the thousands each year. These streams vary in 

 size from large river systems to small creeks. Some of the streams 

 are more or less isolated along unbroken shore lines whereas others 

 are centrahzed in large bays and inlets. Until marking experiments 

 are carried on in streams of both categories, no definite conclusions 

 can be drawn in regard to the degree of homing instinct inherent in 

 the pink salmon. 



The pink salmon in Snake Creek at Ohve Cove and in Anan Creek 

 in Bradfield Canal have been measured each summer for the past 3 

 years in an attempt to determine the differences, if any, in the body 

 characteristics of the salmon composing the populations in the two 



