A UTUMN&^ WINTER EMIGRA TION OF SMOLTS. 1 2 1 



is then that they assume their silvery coat before 

 going to sea. Some of them, however, prefer stay- 

 ing in the fresh water, and do not leave the ponds 

 until the spring following. Therefore we have 

 strong evidence that smolts which go to sea in 

 autumn or winter are not connected with those 

 hatched out from autumn spawners. But there are 

 fish which spawn all through January and February, 

 or two months later than those which spawn in 

 November, whose ova are available for a future 

 supply, although perhaps in limited number. A 

 cold temperature, we are told, retards the hatching 

 of ova, and as the temperature of river water is, as 

 a rule, lower early in the spring than in November 

 and December, January and February, the ova take 

 longer to hatch then than at other times. It 

 may therefore well be, that parr bred from January 

 and February ova are not ready to go to sea as 

 smolts until five or six months later than those bred 

 from November ova. And if so, we have at once a 

 reason for the winter being chosen for the voyage. 



