Translation Series No.1211

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to show in an investigation of the chemical conditions of the salmon eggs
that fat is the most probable source of energy for the development of the
embryo. In addition, fat is being deposited in the gut mesenteries of the
yolksack-brood befors the first intake of food - .
F. Thurow (19 62) was able to demonstrate that the storage of
fat in the Baltic Sea salmon is correlated with the readiness to spawn.
The salmon of the age class A.1+ show during late fall, with
an average of 14 Per cent fat content, a value that is hardly lower than
in fish of three winterS(A.2+). In the winter most of the younger fish
suffer a considerable deterioration in condition, so that the fat content
falls to an average of 6.5 per cent. The larger and older fish are able
4.5s
to keep the food supply so favourable that only a very slight consumption
of fat takes place. Whereas the salmon of two winters lose more than 50
per cent of the fillet fat, this loss in those of three winters amounts
to only 10 per cent, so that their fat content in epring amounts to about
12 per cent. According to this there are two developmental phases during
the sojourn in the Baltic Sea. During the first phase, which ends in general
in the late fall of the second yeaT in the sea, fat is predominantly being
stored up to a content of 14 to 15 per cent. When the fish succeed to keep
the loss in condition so low that the fat content does not sink below about
12 per cent, then these salmon can take part in the spawning emigration
in the spring. In the other case they remain in the Baltic Sea, attain
again a content of 15 per cent fat until November and then survive the
winter so well that they can emigrate to spawn after a three-year stay in
the sea. When we compare these results with the findings of the investig
ations of the oocytes, we find here also the expression of the two phases
. that have been mentioned (Fig. 21)". The formation of the fat depositsi;that