98 REPORT OF THE SECRETARY OF COMMERCE 



The studies recently undertaken on the salmon fisheries of Puget 

 Sound have also been continued with special attention given to the 

 sockeye and coho salmon fisheries. Details of the life history of 

 these fishes have been studied as a basis for future protection, and a 

 statistical analysis of the sockeye salmon fishery of the Frazer Iliver 

 area was made which demonstrates the severe depletion of this 

 important stock of fish and emphasizes the need for international 

 regulation of the fishery. 



Studies have been continued on the two most important species of 

 salmon in Alaska, namely, the red salmon and the pink salmon. 

 Studies of the red salmon of Karluk River system, which require 

 continued observations for many years, were conducted during the 

 past year for the purpose of determining production from known 

 escapements of spawning fish. Eecords for eight generations are 

 now available, showing wide variations in production, varying from 

 a ratio of return to escapement from 0.6 to 1 to 5.6 to 1. There seems 

 to be little possibility of regulating spawning escapement so as to 

 produce consistently a large population. Hence, efforts are being 

 directed to the determining of factors which determine survival in 

 order to control natural forces and to regulate the fishery in the 

 interest of conservation. 



Similar studies of the changing abundance of pink salmon have 

 also been continued in southeastern Alaska. Results of this study 

 show that wide fluctuations may be expected in the yearly abundance 

 of this species. Studies of the effect of rainfall and stream flow, as 

 it affects spawning conditions, and population density in the sea, 

 affecting rate of growth and time of migration, hold the key to 

 better regulation of the fishery. 



Further studies have been pursued of the depletion of the herring 

 in limited areas in Alaska, with a view to determining the units of 

 population that make up the herring supply. Supplementing bio- 

 statistical analyses of the races of herring, large-scale tagging experi- 

 ments have been undertaken to trace the migrations and to find the 

 limits of movement of the various stocks. Recovery of ta^s has been 

 facilitated by the perfection of an electric device for detecting tagged 

 fish in commercial catches. Detailed records of actual migrations 

 are now being secured to guide the drafting of more effective fishery 

 regulations. 



SHELL-FISHERIES INVESTIGATIONS 



Investigation of the various problems relating to oyster culture 

 were carried out in all the principal centers of the industry of the 

 Atlantic and Pacific Coastal States and the Gulf of Mexico. The 

 work was expanded by an experimental study of the effects of oil 

 pollution in Louisiana waters, which demonstrates the dangers to 

 aquatic life of the develoj^ment of petroleum supplies in coastal 

 waters. 



In the New England area the larger part of the work was a con- 

 tinuation of the investigation of the growth and fattening of oysters 

 .started by the Bureau in the spring of 1932. The effects of "water 

 temperature and varying amounts of various chemical constituents 

 of sea water were studied in relation to nutrition of oysters and 

 the storing of glycogen or animal starch. These studies are f unda- 



