410 U. S. BUREAU OF FISHERIES 



on 2.229 of these. The same data were obtained on 1.430 chum sahnon 

 in 36 samples. Length and weight data were taken on 830 pink 

 salmon in IT samples. 



Considerable attention has been given to tracing the early history 

 of the fishery so as to be able to utilize past experience on the effect 

 of the fishery on each species in deciding what effects to expect in 

 the future. 



WASHINGTON COHO SALMON 



The coho salmon investigation on Puget Sound, the purpose of 

 which is to determine the life history of the species, changes in its 

 abundance together with their underlying causes, and methods of 

 rehabilitating population in streams now barren or depleted, was 

 continued during the past year under the direction of George B. 

 Kelez. 



A continuous series of fingerling collections was made in McMillin 

 Creek to determine the rate of growth of the fish from the time of 

 hatching until the time of seaward migration. Because of differences 

 of temperature as great as 10° C. between various streams of the 

 region at the same time in the summer, a series of samples was taken 

 from all major streams and tributaries during the last week in June. 

 A preliminary analysis of this material shows a size range from 34 

 to 59 mm with a mean of 40 mm in the colder streams, and a range 

 from 48 to 71 mm with a mean of 60 mm in the warmer ones. 



Two marking experiments were undertaken this season on Voight 

 Creek, a tributary to the Puyallup River, in the southern part of the 

 region. The fingerlings used were provided through the cooperation 

 of the Washington State Department of Fisheries. In the first ex- 

 periment, 50,000 fingerlings reared from eggs taken in November and 

 hatched during Fei)ruary 1934 were marked by the removal of the 

 dorsal and right ventral fins. The fish marked each day were held 

 24 hours to determine any loss due to handling and were liberated in 

 the stream. This marking was carried on during the period from 

 May 13 to May 19, 1935. For the second experiment, 25,000 fingerlings 

 of the same age hatched and reared at the State hatchery on the 

 Green River were moved to Voight Creek and marked by the re- 

 moval of the adipose and both dorsal fins. The lots of fish marked 

 each day were held for 24 hours in the stream and then liberated. 

 This experiment was carried on between May 28 and June 3, 1935. 



The first experiment is expected to furnish information on certain 

 phases of the life history of the coho salmon such as the "homing 

 instinct", migration routes, and time of appearance of this par- 

 ticular run, through recoveries of adult fish both from the commercial 

 fisheries and from the stream itself during the spawning run. The! 

 second experiment is intended to determine the success of transplant- 

 ing coho salmon of the fingerling size in a stream entirely separate 

 from that of their nativity. Adult fish resulting from the fingerlings 

 transplanted to Voight Creek must pass the mouth of the more 

 northerly Green River, their native stream, before reaching the mouth 

 of the Puyallup. If the tendency is to return to the Green River 

 they will be taken at the hatchery rack there ; the proportion return- 

 ing to the Puyallup will indicate the success of transplanting fish of 

 this size. 



