PROGRESS IN BIOLOGICAL INQUIRIES, 1931 477 



assisted by Morris Rafn. This work has been directed toward secur- 

 in^: a knowledge of the age groups represented in the runs and their 

 relative importance, the time at which fish bound for the various 

 widel}^ separated spawning grounds pass through the commercial 

 fisher}^ at the delta, and the present condition of the fishery. 



A scale study has revealed that the red salmon of the Copper River 

 mature at various ages ranging from 3 to 7 years and live for one to 

 four winters in fresh water before the time of their seaward migra- 

 tion. Only 3 of the 11 age groups represented have been of signifi- 

 cance in any of the recent runs. Of these, the fish maturing in five 

 3'ears, which have spent two winters in fresh water, have been the 

 predominating age group. The relative importance of these age 

 groups has changed with some degree of regularity during each 

 season. 



For the purpose of determining the time at which the salmon that 

 spawn in the different tributaries pass through the gill-net fishery at 

 the delta, records have been obtained of the daily catch by the com- 

 mercial fishery at the river mouth, by the Indian fish wheels distrib- 

 uted along the entire length of the river, and by gill nets operated in 

 some of the more important tributaries. The runs, so obvious at the 

 mouth of the river, may be traced to their ultimate destination by 

 this method, and regulations may be promulgated to provide ade- 

 quate seeding of each spawning area. The collection of uniform 

 statistics has been facilitated by the use of forms prepared for that 

 purpose. 



In connection with these observations data have been collected 

 which are designed to show whether or not the salmon utilizing dis- 

 tinct spawning areas of the Copper River develop physical charac- 

 teristics by which they may be distinguished. The analysis of these 

 data is not yet complete. 



An effort has been made to determine the extent of the spawning 

 beds of the river and its tributaries. With this proposition in view, 

 the seeding of the known spawning localities is observed annually. 

 Much of the river system, because of the difficulty of access during 

 the summer months, has not been explored and new spawning areas 

 are being discovered each year. 



Bristol Bm/ red salmon. — A. C. Taft, who was formerly in charge 

 of the Bristol Bay red-salmon investigation, was transferred to other 

 work during the latter part of 1930. T. L. Schulte carried on the 

 necessary field work in this locality during the summer of 1931. 



A very extensive collection of downstream red-salmon migrants 

 was secured from Aleknagik Lake, its tributaries, and Wood River. 

 Total length and body measurements have been made of these speci- 

 mens and samples of the scales have been mounted. These data 

 upon analysis should yield much information regarding the early 

 life histoiy of the red salmon of the Wood River and its tributary 

 lakes and streams. 



Scale samples were also collected from adult red salmon caught 

 both in the Wood River system and in the commercial fishery in 

 Bristol Bay itself. Trips of inspection were made to the other 

 principal fishing areas in Bristol Bay. 



