232 FLY FISHING AND SPINNING 



insect life, the young of other fish, worms, small eels, and 

 water shrimps ; and when the supply has been plentiful it 

 will have grown, until in the following spring its length is 

 from 5 to 7 inches, and its weight from 2J to 3J ounces. 



THE SMOLT 



In the first, second, or third spring succeeding its 

 appearance as an alevin a gradual change takes place in 

 the parr as its smolt stage approaches. It seldom rises 

 at a fly, its body gradually acquires a scaly covering, and 

 the beautiful markings of the parr state disappear beneath 

 this new and protective armour. (See Plate XXVIII.) 



During these spring months it and the other parr who 

 have also changed their appearance and entered the smolt 

 stage, urged by that instinct which has so far guided them 

 in safety, with one accord make their way rapidly to the sea. 



Mostly following the sides and shallow parts of the 

 stream, but in the dangerous rapids keeping well down in 

 the river channel, they drop down stream towards the sea ; 

 at times they may be seen flashing like bolts of silver down 

 the cascades and shooting over the caps of the big falls. 

 Passing gradually from the purer and colder waters of the 

 upper river into the muddy and warmer waters of the tidal 

 reaches, they finally emerge into the cool, food-abounding 

 paradise of their ocean inheritance. 



A considerable difference of opinion, however, exists 

 as to this change of the parr into the smolt not only as 

 regards the percentage of fish in each year's hatch which 

 leave in the spring of the following or succeeding year, but 

 also as to the sex of those which change during these years. 



It has so far been impossible to determine this question 

 with certainty, even in regard to the results of each par- 

 ticular year's hatch of domesticated alevin. How much 

 more difficult is the problem where wild fish have to be 



