468 Dr KM ox on the Natural History of 



a certain extent, the excellent qualities of the fish as an article 

 of food. Something, however, must be ascribed to a specific dif- 

 ference in the fish itself; for though we have ascertained that the 

 salmon-trout lives very much in some localities on the same kind 

 of food as the true salmon, yet under no circumstances does this 

 fish acquire the same exquisite flavour as the true salmon : hence 

 the real habitat of the true salmon is the shores and bays which 

 most abound with this kind of food. When the salmon first takes 

 to the estuary and to the river, whether beyond or within the in- 

 fluence of the tide, he does not feed unless the estuary should hap- 

 pen to contain this peculiar kind of food ; food congenial to other 

 and analogous fishes, (however closely they may be allied to him) 

 is neglected by him * ; and as in no case can he find his proper and 

 peculiar food in fresh water, he deteriorates constantly whilst 

 he remains. Neither the estuary, the brackish water, and much 

 less the fresh water river constitute his habitat ; he takes to 

 them solely on account of their being comprised within the 

 range of his migration. Many salmon ascend and descend rivers 

 with every tide, and, like their congener the trout, rush up ri- 

 vers when flooded. The regulating cause of such movements in 

 the trout is, I am satisfied, the search for food ; but every fact 

 disproves this application to the salmon. Their farther migra- 

 tion up rivers beyond the influence of the tide, will be explained 

 when we speak of the history of salmon as a smolt. To go further 

 into this matter here would but lead to repetition. On the other 

 hand, the salmon-trout is by no means so nice in respect to food. 

 Besides preying on the food of the true salmon, it takes very 

 readily the sand-eels and herring fry ; and these it finds in more 

 or less abundance in estuaries and at the mouths of rivers. Thus, 

 both in its specific nature, and in respect to its indiscriminate 



* Experiments are wanting to determine to what extent the spawned salmon of 

 the true salmon kind feed in rivers during the spring months; but on this, as on 

 most of the disputed points, see the Appendix generally. 



