84 THE AGE AND GROWTH OF SALMON AND TROUT. 



l>y sub-headings, showing whether they migrated when two, three, four, or 

 five winters old, and how large they were on the date of capture. In the 

 final column is given the size and the total number of fish caught of each 

 year-class divided according to the number of winters completed subsequent 

 to migration. 



At the foot of the table we have the total of the various sub-divisions, 

 together with their average length. 



From this table we can read the following : 



The number of years of river life before migration. 



The years of sea life before spawning. 



The relative occurrence of previous spawners. 



The average length in centimetres of the various age-classes. 



From the arrangement of the dating at the head of the column we can 

 also readily tell the year when the fish were hatched. 



In a similar manner the same material has been divided and arranged 

 according to the fish's weight (see Table XL). 



All averages are reckoned from the original tables, which were after- 

 wards arranged for printing purposes, so that the length classes were in 

 divisions of 8 centimetres, and the weight classes of 7 hectograms. 



In the same way the whole of the material has been arranged in 

 separate tables for each locality. 



From these tables we can obtain information on the two following 

 points in the life history of the fish which I now propose to discuss 

 separately, and which I shall endeavour to further elucidate with the help 

 of other material in my possession. 



(a.) The Age of the Smolt at Migration. 



In the table below I give the total number of fish from each of the 

 various districts, examined in 1908 and 1909, and in the separate columns 

 is shown how many of these migrated after an age of two, three, four, or 

 five winters. 



1908. 



