OA U. S. BUREAU OF FISHERIES 



No tagging experiments were conducted in southeastern Alaska 

 during the summer of 1937. owing to the lack of suitable equipment 

 and funds. The returns from the 1935 and 1936 taggings were 

 studied and a detailed report has been submitted showing the migra- 

 tion routes of pink salmon through Clarence Strait and adjoining 

 waters. It is shown that fish tagged at various time intervals during 

 the spawning migration are bound for widely separated areas. 

 Knowledge of this change in migration as the season progresses pro- 

 vides an explanation of the seasonal shift in the fishery and therefore 

 aids in the establishment of the various boundaries for each dis- 

 trict. This tagging report covers both the odd and even year groups 

 and indicates the peculiar migration characteristics of each popu- 

 lation. 



Weir counts taken at Little Port Walter this year gave the second 

 set of returns from a known even-year escapement and the first re- 

 turns from a known odd-year escapement. A total of 7,085 pink sal- 

 mon from the 1935 spawning population were counted through the 

 weir from August 16 to September 10. Previous weir count totals 

 consisted of 6,952 pink salmon in 1934, 6,073 in 1935, 5,161 in 1936, 

 and 7,085 in 1937. The 1937 escapement is a 17 percent increase over 

 the 1935 spawning population, while the 1936 returns were a 26 per- 

 cent decrease under the 193-t population. Causes for such fluctuations 

 can only be determined through a study of natural and imposed 

 mortality from one point in the life cycle to the corresponding point 

 in the life cycle of the following generation. 



The sex of the individuals composing the run was determined as 

 the salmon passed through the weir. This was accomplished with the 

 aid of a specially constructed pen just above the counting gate which 

 enables the observer to determine and record the sex of the individual 

 fish as they pass through. In this stream males predominate at the 

 beginning of the season, the ratio in some days running as high as 90 

 percent. This excess of males continues until the run is about three- 

 fourths complete at which time the ratio stands at 2 to 1. During 

 the last quarter of the run the females increase in abundance to such 

 an extent that the ratio of sexes for the season as a whole is balanced. 

 Factors influencing sexual development were observed throughout the 

 season and actual weights of the gonads were taken at various inter- 

 vals to determine percentage change in weight of sexual products 

 over body weight. 



Egg counts were taken to determine the average egg deposition 

 that could be expected for the 1937 run. The average number of eggs 

 produced per female in 1937 was 2,059, which resulted in the deposi- 

 tion of approximately 7,293,000 eggs in the gravel beds of the stream. 



Three samples of the run were taken during the season for racial 

 analysis measurements. From 26 body measurements taken from 

 each individual a number of comparisons are made to determine the 

 significance of individual variation. The continuation of racial analy- 

 sis is expected to provide a method of segregation of various popula- 

 tions which will aid in formulating regulatory measures for future 

 conservation. 



Cooperative work with the National Canners Association of 

 Seattle, Wash., carried on for the third consecutive season at the 

 station, consisted of a study of the physical and chemical changes 

 occurring in the pink salmon run at Little Port Walter. Daily 



