THE FEEDING OF SALMON 123 



course freely admit ; but, as suggested in the chapter 

 on grilse, it is possible to regard the first seaward 

 migration as a movement to the salmon's original 

 habitat, i.e., the habitat from which our salmon as we 

 now know it, along with its near allies, took its origin 

 in remote times. The shad is a sea fish which visits 

 our rivers to spawn. The spa.rling or smelt must be 

 similarly regarded, and is more nearly related to the 

 salmon than the shad. Attempts at producing 

 fertile salmon without allowing them to visit the 

 sea easily fail, and when successful, result in 

 degenerate creatures which do not support the idea 

 that they represent the prototypes of fish from 

 which the evolution of our salmon has sprung. The 

 vigorous growth and development in the sea, on the 

 other hand, and the fact that the salmon spends 

 most of its time in this element, along with the 

 arguments already cited in the chapter on grilse, 

 from the systematic study of the salmon family, in- 

 cline me to the view that the sea was the original 

 habitat of Salmo solar, as it undoubtedly was of 

 most of the salmon family. 



If this is so, there is nothing forced in the belief 

 that the long migration fish, continuing in the sea 

 as it must do long after its tissues have become fully 

 nourished, and as the study of the scales certainly 

 indicates, is simply living in its natural habitat. At 

 the same time, I do not consider that the nisus 

 generativus prompts the spring fish to enter fresh 

 water. The late running fish which has already 

 developed its genitalia in the sea may be said to 

 visit the river for the purpose of spawning, but the 



