Translation Series No.1211

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concerns the yield of captures. If we set the total number of the captured
fish equal to 100, we obtain for the three sea year classes shares of 75
22, and 3 Per cent. On the other hand the average values of the age analyses
(Table 33) are 69, 28, and 2 per cent. The parameters ascertained are there-
fore erroneous, so that the model does not agree with the actual conditions.
An alteration of F or of Z changes the percentage of the fish caught in
the second year only unsubstantially. The decisive and important knowledge
to be derived from this fact is the - determinationthat the fishing is sel-
ective, - so that the sea year classes are being exploited - in different de-
grees. The expectatiOn that F is equal in both sea.year ailases is wrong,
P 3 must be greater than F 2 .
The . second . item concerns the number of spawning fish. In Table
57 the number of spawning migrants of the sea year class A.2 issmaller
than the number of three-year-old spawning fish. However, we know already
that the relation is the opposite (5.3.1.3.). With this we have two orit-
! [p. 357]
eria, with the eViofleioh the parameters can be tested. For the final res-
ults it will be of value, to pursue this idea further.
Table 57. Preliminary model of the stock of salmon in
the Baltic Sea.
Coefficients
of
.
Num.
Years at Number Yield of
in .beg,- of fishery
the in. natur..
loss Balt, of losses Number
F T Sea year
. Number
of
spawn. Total
mi-
grants -
1. 6 500 000 5 421 000
5 421 000
0,1
0,1
0,9
0,9
0,2
1,2
2.
.3.
4.
1 079 000
324 995
36 009
62 808
13 134
565 504
118 224
(20 000)
1 700
890
200
125 693
157 628
754 005
288 986
703 728 2 790