Trout and Salmon 175 



TROUT 



The most widely accepted theory about the salmonids 

 holds that they originated in the Arctic as migratory fish. 

 When the ice came down across the parts of the world in 

 which we now live, they came with it. When the ice retired 

 and the seas grew warm again, colonies of them which had 

 become fresh-water dwellers were trapped in the cool streams 

 they had entered — some as far south as the Atlas Mountains 

 in North Africa — and have remained there ever since. Cut 

 off from each other in these streams, the differing conditions 

 brought out different hereditary tendencies. And from this 

 arose the bewildering number of species and subspecies and 

 races and varieties of trout which make life difficult for the 

 taxonomist — the man whose job it is to interrelate and 

 classify and name the forms of animal life. For the trouts, 

 as we have said in an earlier chapter, are still in a state of 

 evolutionary fluidity. Species and subspecies are still being 

 formed, and only a few years ago a new one was described, 

 the beautiful little Salmo selenins Snyder, the "moon-rain- 

 bow" trout, inhabitant of the headwaters of a small stream- 

 system in California. 



Up to a few years ago zoologists felt that it was desirable 

 to seize on comparatively minute differences to split trout 

 up into different species. If these "splitters" had continued 

 on their way, it would not have been long before every 

 stream and lake had its own distinct species. Recently the 

 trend has changed. Splitting is looked on with less favor, 

 and the tendency is to take all trout which are not separated 

 by clear-cut, permanent differences and lump them together 

 in one species. The "lumpers" now believe that all the Eng- 

 lish trouts, from the smallest inhabitant of the smallest burn 

 to the largest ocean-going "sea-trout," are nothing but vari- 

 ations of one and the same species. They likewise believe 



