478 U. S. BUREAU OP FISHERIES 



ALASKA PINK-SALMON INVESTIGATIONS 



This investigation is concerned with the study of the life history 

 of the pink sahnon {Oncorhynchus gorhuscha). During the past 

 year the following experimental studies were pursued under the 

 supervision of Dr. F. A. Davidson : 



Application of " parent stream " theory to life history of pink 

 sahnon. — The experiments underlying this study consist of marking 

 pink-salmon fry from a given stream as they leave the stream by 

 means of clipping the dorsal and adipose fins from their backs. This 

 is followed by a careful observation of the adult pink salmon, return- 

 ing to the stream two years later to search for individuals bearing 

 the marks. These experiments were started in the spring of 1930 at 

 the Duckabush (Wash.) hatchery on Hood Canal, where 36,000 pink- 

 salmon fry were marked. In the fall of 1931 the pink salmon that 

 returned to other streams on the canal, as well as those returning to 

 the Duckabush River, were observed for adults bearing the marks. 

 Eight adult pink salmon, consisting of males and females, showing 

 both dorsal and adipose marks were found in the Duckabush River. 

 One adult female was found in the Hamma Hamma River, located 

 just north of the Duckabush River, and one adult male was found in 

 the Docewallips River, just south of the Duckabush River, both of 

 which showed both dorsal and adipose marks. An examination of 

 the scales of these marked salmon showed that the time of their 

 return as adults coincided with their age indicated by the checks on 

 their scales. 



In the spring of 1931, in Snake Creek, at Olive Cove, Alaska, 50,000 

 pink-salmon fry were marked by means of clipping their dorsal and 

 adipose fins. These fry are expected to return in the fall of 1932. 

 The marking experiments in Alaska are being supplemented by racial 

 analysis of the pink salmon in the streams in which fry are marked. 

 During the summers of 1930 and 1931 the pink salmon in Snake 

 Creek and the pink salmon in Anan Creek, a neighboring stream, 

 were studied from the racial standpoint. 



Vanation in time of appearance of pinh-salmon runs in south- 

 eastern Alaska. — Through the courtesy of the salmon packers operat- 

 ing in southeastern Alaska, the bureau secured the records of the 

 daily pink-salmon catches of a large number of salmon traps located 

 in the various fishing districts throughout the territory. These rec- 

 ords in general cover a period of time from 1908 to 1930, inclusive, 

 and are believed to be representative of the changes that have been 

 talring place in the status of the fishery. 



Since the salmon traps are stationary units of gear and more or less 

 permanently located, it was assumed that the time of appearance of 

 the pink-salmon runs in any district would be indicated by the time 

 in the fishing season the pink-salmon catches were made by the 

 salmon traps located in the district. With this assumption in mind, 

 a statistical analysis was made of the daily pink-salmon trap-catch 

 records of the salmon traps located in each fishing district in the ter- 

 ritory for the purpose of ascertaining variations in the time of run. 



A similar analysis of the daily pink-salmon packs of a south- 

 eastern Alaska cannery showed that from 1895 to 1909 the pink- 

 salmon runs were much later than they are at the present time. In 



