LIFE-HISTORY OF THE COHO 43 
SESSIONAL PAPER No. 38a 
of the second year varies from 11-1 to 18-1, with an average of 14-3. The highest 
point of the curve is reached with 13-5, but there are several others nearly as high. 
That, in general, the yearlings that have the best start tend to keep it up, is shown 
by the fact that the average of the length at the end of the first year, added to the 
average growth in the second year, gives exactly the length at the end of the second 
year. For the growth in the third year, only those caught after September 15 are 
considered. Since there is such rapid growth during the third summer, a fair com- 
parison could not be made of all those caught during the year. Apart from an 
abnormally small growth, 4-0, and an abnormally large one, 14-2, the growth for the 
portion of the third year varies from 6-1 to 13-5 inches, with an average of 9-7; 10-0 
has the highest point on the curve, with 9-5 and 10-6 nearly approaching it. The 
total length at time of catching of these same third-year specimens varies from 18-0 
to 31-0 inches, with an average of 24-0. The highest point on the curve is taken by 
23-0, but 22-0 and 23-5 nearly equal it. As the frequency curve here is made from 
half-inch measurements while the others are in tenths, they are not exactly compar- 
able. Here again the average length is equal to the sum of the average growth in 
the three periods, 3-3 + 110 + 9-7 = 24-0, and the length at the end of the three years © 
is 3-3, 14-8, and 24-0, respectively. 
The fish that went to sea as fry were not sufficiently numerous to serve as a basis 
for definite conclusions. The measurements were as follows :— 
1. At end of 1st year, 9°6; 2nd year, 16°4; 8rd year, 24°0 
2. ee oe 11°0 “ 19°4 “ce 25°0 
So “ec it 11°4 ““ 21°5 Ti 28°0 
Average ‘“ se OST e 19°1 « 25°7 
There is no very appreciable difference between the length of the males and the 
females. The averages are:— 
Males —At end of 1st year, 3°83; 2nd year, 14°5; 38rd year, 24°1 
Females— ‘“ ss 33: ss 14°2 ss 24°0 
There is more difference between the average lengths of those caught at Neah bay 
and those caught in the strait of Georgia. 
Strait of Georgia—At end of 1st year, 3°3; 2nd year, 14°1; 3rd year, 23°7 
Neah Bay —- st ss 3°6 eS 15°5 Ce 25°6 
If the difference was in the third year only, it might be accounted for partly by 
the fact that those from Neah bay were caught a little later in the year than the 
majority of those taken in the strait of Georgia, but the difference is relatively as 
great at the end of the second year, and is noticeable even at the end of the first year. 
It might be that since all of the Neah Bay specimens were from the same lot, that 
was an early spawned lot and they were able to keep up the initial advantage. To 
keep up the advantage it would be necessary to have the proper supply of food in 
any case and probably the food supply is better at the entrance to the strait of 
Fuca or somewhere in that vicinity than it is in the strait of Georgia. This is borne 
out in the comparison of weights, a matter which is taken up later. 
The length at the time of migration varied from 2-8 to 6-6 inches, with an 
average of 4-5. Out of the whole number only eight were over 6-0 inches, and only 
twenty-two were over 5-5. The greatest number were at 4-6. Various calculations 
were made to see if the fish were ultimately smaller on account of the longer time 
spent in the fresh water at the beginning of the second year, but no constant differ- 
ence could be found even in the growth for the second year. The time of hatching, 
and consequently the length at the end of the first year, seems to have more to do 
with the total growth and the second year’s growth than the length of time spent in 
the fresh water during the second year. Possibly if a greater number were examined, 
some difference might be shown. 
