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MIGRATION OP THE SALMONIDiE. 

 Part II. 



PERIODS OP MIGRATION. 



By FRANCIS DAY, C.I.E., F.L.S., &c, 



President Cheltenham Nahcral Science Society; Author of a 1 History of the Fishes 

 of Great Britain and Irelaitd,' &c. 



In the first portion of this paper I discussed the question of ' early ' 

 and ' late ' salmon rivers, and have now to consider the migrations of 

 the salmon during different periods of the year, as well as some of 

 the numerous statements that have been advanced. These fish, as 

 we know, are 'anadromous,' being forms which enter our rivers chiefly 

 to perpetuate their race ; for this purpose they select suitable spots 

 wherein to deposit their eggs ; here the young are hatched, while they 

 remain in. the stream for the first years of their existence. Conse- 

 quently, during their youth they live and feed in fresh water ; as they 

 grow older they descend to the sea, from whence, after a time, they 

 return to the rivers ; thus the waters they select for their residence 

 differ from each other in their specific gravity, taste, temperature, and 

 products. 



I do not intend following out the life history of these fishes from 

 the rivers where they were born and the fresh waters which they as 

 smolts deserted for the ocean, returning again as breeding grilse, which 

 again descended to the sea after they had propagated their kind, but 

 I propose offering a few remarks as to how they subsequently migrate 

 to our coasts and to our rivers. For where they pass their sojourn 

 in the deep does not at present much concern the practical fisherman, 

 who only troubles himself as to how he can capture them, while the 

 fish-culturist is aware that their eggs will not hatch if deposited in 

 salt water. 



These migrations from the sea are, broadly speaking, of two kinds : 

 firsts what may be generally described as the great autumn and winter 

 one, for the purpose of spawning ; and secondly, much more irregular 

 ascents, consisting of a few or many fish, occurring throughout the 

 year, or restricted to certain months. This inquiry would embrace 

 several considerations, such as the following: — How do salmon return 

 from the sea to our coasts ? How do they enter and continue in 

 estuaries prior to their ascent into the stream ? How do they ascend 

 rivers ? How do they return to the sea ? 



As a general rule, as I have observed when under the head of 

 ' early and late salmon rivers,' these fish migrate towards rivers sooner 

 from cold seas, as the German Ocean on the east coast of the British 



April 1886. 



