88 REPORT OF THE COMMISSIONER OF FISHERIES. 



the salmon industry, to the end that a clearer understanding of the 

 problems involved might be obtained. 



Incidental to the salmon investigations numerous dredgings were 

 made by the steamer Alhafross at various depths in the straits and 

 fiords of southeast Alaska and about Kadiak Island, Afognak Island, 

 and Yakutat. These investigations had in view the development of 

 the aquatic fauna of Alaska, and resulted in large and interesting col- 

 lections, not only of fishes, but of moUusks, crustaceans, and other 

 invertebrates. These collections have been assigned to specialists for 

 study and report. 



The salmons of the Pacific. — The salmons of the Pacific differ nota- 

 bly, as a whole, from the single species called salmon (Salmo solar) on 

 the coasts of the North Atlantic. Anatomically they differ in several 

 details of structure; in habits the distinctions are still more marked. 

 Normally, the Atlantic salmon survives the reproductive act and 

 returns to the rivers at the spawning time for several years. The 

 Pacific salmons, on the other hand, have more definite runs. The 

 greater part of their lives is spent in the sea, and they run into fresh 

 water only at spawning time. During this period they take no food 

 of any kind, the oil of the body is consumed, the flesh becomes dry 

 and pale, the jaws of the males become much elongated and distorted, 

 the front teeth are enlarged, the color is changed, and the whole body 

 becomes greatly distorted. Death follows within a few days after 

 spawning. There is no evidence that any individual of any species of 

 Pacific salmon ever survives the reproductive act. 



All the Pacific salmons spawn on a falling temperature, when the 

 water is already cool and becoming colder. Freezing kills the eggs, 

 but any temperature between 54° F. and freezing is favorable to their 

 development; above the former point the eggs develop precociously 

 and the young fish are apt to die. In the more northern rivers a 

 temperature of 54° is reached earlier, and for this reason the run 

 of salmon occurs earlier in those regions than in the southern waters 

 of Alaska. All the species spawn by preference in running water, 

 though occasionally some individuals spawn in lakes. The spawning 

 beds are usually on gravel bars, and in the spawning act the gravel is 

 pushed about, not for the purpose of covering the eggs, but rather as 

 a part of the spawning act itself; pressure against the gravel aids in 

 the extrusion of the eggs. The male covers the eggs with milt, and 

 in so doing also moves the gravel about to some extent. This fact is 

 a matter of importance where different species, or different schools of 

 the same species, spawn upon the same beds, the later comers disturb- 

 ing more or less seriously the eggs of those which have preceded them. 



There are five species of salmon in Alaska and neighboring waters, 

 and they are identical with the species found on the coasts of British 

 Columbia, Washington, Oregon, and California. These five species 



