Growth and Development of the Salmonidcz. 1 6 1 



When the alevins of trout or salmon leave 

 the shell, they are about three-quarters of an 

 inch in length. In about three or four weeks 

 the yolk-sac is absorbed, this result being hast- 

 ened by a higher temperature, or retarded by 

 a lower one. The young salmon then becomes 

 a parr, and soon the parr-marks can be distin- 

 guished ; and at three months old, when about 

 two inches in length, these marks are clearly 

 developed. At six months old, the parrs have 

 attained to an average length of three inches, 

 some having reached four inches ; at nine 

 months old, their length is four to five inches; 

 and at twelve months, some will have reached 

 seven to seven and a half inches ; while the 

 bulk of them remain about five to five-and-a- 

 half inches long, and some, even then, are not 

 over three inches. At this stage a transforma- 

 tion takes place in the migratory species. The 

 salmon parr puts on a coat of silvery scales, 

 covering the parr-marks, which can still be 

 seen on removing the scales, which are loosely 

 attached, and come off easily on handling the 



fish. 



This change takes place immediately before 

 the fish begins its journey to the sea, and the 



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