SALMON AND SALMON STREAMS OF ALASKA. 165 



THE SALMON AND SALMON STREAMS OF ALASKA. 



By President DAVID STARR JORDAN, 



LELAND STANFORD JUNIOR UNIVERSITY. 



The Salmon of the Pacific. 



nnHE salmon of the Pacific differ notably as a whole from the single 

 -*- species called salmon (Salmo salar) in the Atlantic. Anatomic- 

 ally the Pacific salmon (Oncorhynchus) differ from the salmon of the 

 Atlantic (Salmo) in the greater number (14 to 20) of developed 

 anal rays (the Atlantic salmon having 10 to 12), in the greater 

 number of branchiostegal rays, 13 to 16, the Atlantic salmon having 

 about 11, and in the usually larger number of pyloric caeca, 65 to 180, 

 the Atlantic salmon having 65. In habits, the distinctions are still 

 more marked. The Atlantic salmon spavens in the small streams and 

 runs in the rivers in the fall for a long distance. In the run, the 

 males become hook-jawed and somewhat distorted and many are 

 attacked by fungus, dying before reaching the sea. But they attempt 

 to reach the sea, and a large percentage of them revive, to spawn again. 



The Pacific salmon, Oncorhynchus, have more definite runs. In 

 the process of running, they take no food of any kind. The oil in 

 the body is consumed, the flesh becomes pale, the jaws in the males 

 become much elongated, the front teeth are enlarged, the color is 

 changed and the whole body is greatly distorted. After spawning the 

 fishes drift tail foremost in the stream, and all die within about a week. 

 There is no reason to believe that any individuals of any spceies of 

 Pacific salmon survive the reproductive act. 



All the salmon spawn in cold or cooling water. The eggs are 

 hatched when the water cools to 54°. Freezing kills them but any 

 temperature between 32° and 54° is favorable to their development. 

 Any temperature above 54° causes the egg to develop precociously 

 and the young salmon dies. The temperature of the streams of the 

 north fall earliest to 54°. For this reason, the run is earlier in 

 northern waters than in southern ones in Alaska. All the species 

 spawn in flowing water, the male with its tail scooping out the gravel 

 in which the female deposits the eggs and over which the male casts 

 out the milt. 



The Species of Pacific Salmon. 



There are five species of salmon in Alaska and neighboring regions. 

 These differ widely in habit and in value, a matter of vital importance 

 to an understanding of the salmon question. 



