Translation Series No.1211

•
'Table 55. Values of the total mortality (by using the
captures by net per unit effort).
Season
Number of salmon/100nets
Total A.1+ A.2+ A.3+ A.1+ A.2+
_
1956/57
1957/58
1958/59
1959/60
1960/61
1961/62
1962/63
7,5
9,2
13,3
10,5
. 8 , 5
10,0
8,0
5,8
.5 , 0.1
9,6
5,2
6,6
9,0
5,9
1,6
3,6
3,2
4,9
1,8
0,9
1,9
0,1
0,5
0,4
0,3
0,1
0,1
0,1
0,48
0,45
0,67
1,06
1,99
1,55
1,16
2,20
2,36
3,89
2,89
2,20
• Min e . = Mean 1,03 2,45 .
- 20 2 -
(N. N. 19 6 2). The values obtained with this method amount te an aver-
age in the Second year Z 2 = 1.15 and in the third year to z 3 = 2.74..
Table 56. Determination of Z with the aid of the virtual
population.
• Number of salmon caught Coefficient of f -Ff•
Season
-
the total loss
n n+1
-
Total A.1+ A.2+ A.3+ Z 2 z3 2
\ \ \
1956/57 93 200 71 800 19 500 1 800 1,31 1,94 4,68
1957/68 49 700 26 900 19 400 2 800 0,58 2,37 3,96
1958/59 62 600 45 000 15 000 1 800 0,96 2,71 3,94
1959/60 36 900 18 100 17 300 1 000 0,42 3,36 4,56
1960/61 55 400 42 800 11 900 600 1,71 3,67 5,16
1961/62 86 000 77 800 7 700 300 1,94 2,40 5,43
1962/63 47500' 35 300 11 100 700
mind. = Mean 1,153 2,742
•
1 On account of the ice conditions only 32,400 salmon were
caught in six Months. For the determination of Z the cor-
responding figure for 8.8 months = 47,500 salmon had to be
used as basis.
Kandler (1964) has also used the total German landings as basis
for the determination of Z. The division of the yields into the age classes,
howevei", waS carried out with the aid of the divisons by weight (cf. 5.33.).
The mean Value obtained by him for 1958/64, Z = 1.14, agrees quite well
with the values found here.