Translation Series No.1211

Year's
set
1956 • A.1 +
4 34 53 8
1
A.2 ±
11 32 50 6
1
1957 A.1 +
A.2 +
1958 A.1 -I-
A.2 +
'At +
• A.2 +
3 24 64 8
' 22 • 34 44
1959 1
1960 A.1 +
A.2 ±
•Avérage
1956-1960
A.1 +
A.2 +
- 174 —
obtains the values in Table 46. It will be seen that the shares of the
elass
age groups of a yeal-4-s—ee4-of smolt change with increasing age.
The percentages of the older fish (3.14 4,B and 5.B) become.
.smaller at the rate at which the shares of the younger fish (1.B and 213)
increase. These changes have no other explanation than that the older
fish emigrate in order to spawn. That means that the sexual maturation
is being determined not only through the duration of the
but also through the duration of the stay in the rivers.
not the du;s.tion of one of the two periods by itself is
total age.
stay in the sea,
LP.333]
In other words,
decisive, but the
Table X. The percentage composition of the sea year classes.
Sea yeax Share of the age groups in the sea
year classes in per cent
class • 1.B 2.B 343 4•B 5.B
4 31 46 17
10 34 41 14
30 51 11
13 34 45 8
5 26 52 15
10 42 43 5
5 29 53 12
13 35 45 7
• At other places it has been pointed out repeatedly' that the
'emigration is connected with the size of the salmon (3.2.3). Applied to
the above statement, this does mean nothing else but that within a sea
,.year class and within its age groups the larger fish mature earlier.
It is therefore possible that the statements about the existing stock are
'correct when calculating the mean lengths. The rates of growth that have
2
1 '
1
2
1