THE 



POPULAR SCIENCE 



MONTHLY. 



JULY, 1902. 



STUDIES IN THE NATURAL HISTORY OF THE 

 SACRAMENTO SALMON. 



BY cloudsley rutter, 



ASSISTANT, U. S. FISH COMMISSION. 



r T^HE following notes are derived mainly from a series of investiga- 

 -*- tions carried on under the direction of the U. S. Commissioner 

 of Fish and Fisheries, by whose permission they are here used. 



The Pacific salmons, the genus Oncorhynchus, of which there are 

 five species, are very distinct from the Atlantic salmon of the genus 

 Salmo. In fact, they have no more right to the name salmon than 

 wolves have to the name fox. Anatomically the two genera do not 

 differ greatly — Oncorhynchus having 14 or more rays in the anal fin, 

 and Salmo 10 to 12 — but physiologically and in life-history they differ 

 in a marked degree. 



The most important difference lies in the fact that the Pacific 

 salmon, of whatever species, dies immediately after spawning once. 

 This is true of both males and females, and is a very remarkable 

 characteristic. It is often denied upon a priori reasoning, the common 

 argument being that, if they all died on the spawning beds the rivers 

 would be full of dead salmon floating down stream. But the common 

 idea that dead fishes float is erroneous. Those that die a natural death 

 do not float, and the salmon is not an exception. 



Natural Propagation. 



Under natural conditions, the female salmon extrudes the ova, a 

 few at a time, in a swift current near the bottom of the stream. Many 

 are carried several feet, or even yards, down stream by the current, and 

 are nearly always devoured by other fishes, such as the trout, sculpin, 



