28 THE ROYAL SOCIETY OF CANADA 
2. The fish of both groups spend their first winter in fresh water, 
descending to the sea in the following Spring. In the case of the Sockeye 
there is evidence that certain individuals remain in fresh water an 
additional year, descending to the sea in their second Spring. 
3. The fish of the first group spend as a rule four summers and 
three winters in the sea, returning to fresh water in the fourth summer. 
Those of the second group spend but two summers and one winter in 
the sea, returning to fresh water in the second summer. 
4. Certain individual Sockeye, Spring Salmon and probably also 
Dog Salmon return to fresh water as grilse. All the grilse examined 
were two year old fish. 
5. The great differences in size of adult Spring Salmon are not 
due to differences in age. All fish of this species of about 65.0 em., in 
length and upwards were four years old. The differences in size probably 
depend on differences in the quality of the food supply encountered 
during the life in the sea. 
6. No evidence was obtained showing that the fish of any species 
spawn more than once in their lives, except that in the case of one Dog 
Salmon there were indications that it had spawned as a grilse and 
subsequently had returned to the sea. 
7. The markings on the scales and otoliths would seem to show 
that the fish during their stay in the sea do not seek the very deep water, 
but remain at depths at which the seasonal variations of temperature are 
distinctly appreciable. 
University of Toronto, 
January 30th, 1912. 
