160 The Pacific Salmons 



in places which have been covered with fungus, 

 parasites attack the gills, and death mercifully 

 ensues. 



The number of eggs deposited by the quinnat 

 is about three hundred or four hundred for each 

 pound weight of the parent fish. The loss of 

 eggs under natural conditions is large, owing to 

 non-fertilization, to destruction by other fish, and 

 to death by being covered with gravel and sand. 

 The investigations of the United States Fish 

 Commission indicate an average loss of eighty- 

 five per cent from these causes. The eggs which 

 are unmolested hatch in seven to ten weeks in 

 California (four or five months in Alaska), and 

 the alevin stage lasts six weeks longer, during 

 which a further heavy mortality amounting to 

 twelve or thirteen per cent occurs. After the 

 young begin to swim they are comparatively free 

 from enemies, and the seaward migration is ac- 

 complished without noteworthy diminution in 

 numbers. 



The duration of the ocean life of the salmon 

 has not been determined, but recent experiments 

 in the marking of fry have shown that in Cali- 

 fornia and Oregon the quinnat salmon come 

 back to spawn in the second, third, and fourth 



