Translation Series No.1211

• 6.1. Previous investigations 175
6.1.1. The nutrition of the juvenile stages 175
6.1.2. The food in the main basin of the Baltic Sea 177
6.2. Amount and kind of food according to my investigations
1957 -6 4 180
6.3. Differences in the composition of the food 182
6.3.1. Seasonal variation 183
6.3.2. Differences on the fishing grounds 186
6.3.3. Differences depending on the kind of fishing gear . 187
6.3.4. Differences depending on sex 188
6.3.5. Differences in food related to the size or the
salmon 189
6.4. The relation between the behaviour of the prey and the
composition of the food of the salmon 190
6.5. The food consumption of the salmon 191
7. Attempt at a quantitative analysis of the stock in the main
basin of the Baltic Sea 194
7.1. The characterization of the stock 195
7.2. Losses in the exploited stock 197
7.2.1. Total mortality 198
7.2.2. Wasting through fishing and natural mortality . . . 203
7.2.2.1. Results of tagging 203
7.2.2.2. Determination with the aid of the fishing
intensity 205
7.3. Losses in the recruitment phase 211
7.3.1. The natural enemies 211
7.3.2. The mortality un til the beginning of exploitation, . 213
7.4. Models for the stock of salmon in the Baltic Sea 215
Summary 221
References 223
Appendix 230
Introduction
The genUs Salmo belongs together with the genus Oncorhynchus
to the subfamily Salmonininae (Family Salmonidae, Suborder Salmonoidè4
Order Clupeiformes) (L.S.Berg 1958). The Atlantic salmon,'Salmo-salar
occurs in the northern part of the . Altantic Ocean. The distribution reaches
from Cape Cod to the Duero River (Spain) in the south and,from West Green-
land to the Kara River (east of Novaya Zemlya) in the north (G. W. Nikolski .
1957).
1 •
The lifè cycle runs'a very uniform course everyWhere in the .
'entire area of distribution. After a period of ,feeding in the beal:the
.