Prince. — Why Do Salmon Ascend from the Sea? 139 



become slowly elevated with the rising of the land and afforded 

 drainage for rains and melted snows from the mountains and raised 

 upper areas, the salmon's habit of seeking the accustomed spawning 

 locality still persisted unaltered. The salmon must needs find 

 its way up the tortuous and often difficult channels that afford 

 the only access to lakes and streams where it was hatched and 

 reared. 



Such typical sea-fish as the Gadidas seem to lend support to 

 my hypothesis. Some, such as the Tom-cod (Gadus tomcod) 

 habitually prefer brackish water; but others, like the Lake Cusk or 

 Ling {Lota vulgaris) have assumed the strictly fresh-water habit.* 

 The smelt, flounder, candle-fish or eulachon, capelin, and other sea- 

 fishes often migrate into fresh water, and some become wholly 

 non-marine; even the hake (Phycis chuss) is found at times far 

 up rivers, where the salinity is low, and where (as in the Kenne- 

 becasis, New Brunswick) they can be taken with baited hooks 

 through the ice in winter. A variety of sea-herring is found in the 

 Baltic, and in fresh- water lakes adjacent, and many Clupeoids 

 occur in rivers and lakes of this continent which never reach salt- 

 water, though the shad and alewives spend most of their life in 

 the sea and resort to rivers only to spawn. 



All changes in nature are gradual, and if a fish, either young or 

 adult, is found to die, when transferred from salt-water to fresh- 

 water suddenly, no argument regarding its ancestral habitat 

 can be based on so unnatural a procedure. There are many 

 Salmonoids like the three or four species of Bathylagus, and the 

 Microstomidas (Nansenia) and the Argentines, which are strictly 

 marine, indeed are deep-sea types ; just as the whitefishes (Coregoni) 

 and the Graylings (Thymalli) are strictly fresh-water, although 

 some species of the former venture into the salty estuaries of 

 Hudson's Bay and James Bay. 



* The European species is reported to occur in the waters of the Upper 

 Baltic, but as Professor Alexander Meek observes, "has not been observed 

 to spawn in the Baltic; and therefore appears to make an anadromous migra- 

 tion."— (The Migrations of Fish, London, 1916, p. 236). 



