190 



THE ROYAL SOCIETY OF CANADA 



'7-0 

 Fig 



1 1 . — Sockeye 



Length at 3 years. 



s/'ô 



responding to this difference in length gives a characteristic difference 

 in the appearance of the central portion of the scale of the mature 

 fish, which usually is sufficient in itself to indicate to which river sys- 

 tem the fish belongs. 



The difference in growth in the second year is more marked. 

 While the Rivers inlet growth is but 6-9 inches, the Fraser river 

 growth is 8 • 5 inches, 23 per cent greater. Thus, while the second year 

 growth of a 4-year Rivers inlet fish is only 31 per cent of the total 

 length that of a Fraser river fish is 39. 



In the third year growth, the difference is still more marked but 

 the situation is reversed. The third year growth of the Rivers inlet 

 fish is much greater than that of any other year, and also much 

 greater than any year of the Fraser river fish. With an average growth 

 of 9-5 inches, there is an excess over the 7-6 inches of the Fraser 

 river fish of 25 per cent and an excess over its own second year growth 

 of 38 per cent. The third year growth of a 4 year Rivers inlet fish is 

 43 per cent of the total growth, while that of a Fraser river fish is only 

 34 per cent. 



In the fourth and fifth years there is little difference in the amount 

 of growth although that of the Rivers inlet fish is slightly greater in 

 both instances. 



It follows from this comparison that there is more difference in 

 the fish at the end of the second year than at any other time in the 



