Translation Series No.1211

- 184 -
Table 49 have therefore been given two figures for every month. The mean
weight of food has been calculated first for the total number of all sal-
mon examined and second only for those fish who had a full stomach.
Botk figures show that the weight of the stomach content is
highest in fall and spring and_lowest during the winter months, especially
from November to March. The investigations of Christensen (1961b) show a •
similar result. It is therefore probable that the food supply of the sal-
mon is smaller in the winter than in summer. On account of the cessation
.of the salmon fishery in summer, we could obtain no samples in July and
August. One can, however, assume that the values for these months would
not be substantially different from those for May/June.
A comparison.with the results of Christensen shows a consider-
..able difference in the amount of food. His values for the season 1960/61
are on an average almost twice as large as the mean values of my material.
Christensen has investigated fresh stomachs that had been collected on
board and frozen, whereas my material had been preserved in formaldehyde.'
It is, hOwever, quite obvious that the large differences cannot have been
caused by different : methods of investigation, but must have thpir cause
• in the better availability of the food in the season of 1960/61.
ye- tin
A glance at Fig. 36 shows that principally the yeeri-s-set of
smolt of 1959 has profited'from the extraordinarily good food supply of
the season of 1960/61. But also thé good growth of the year's sot of smolt
of 1958 during the third year in the sea can be brought into agreement with
this.
$ince seasonal changes in the take-up of food are probable,
we shall once more refer to the, fact that only about one-halUof the eal-
.
mon investigated had food in the stomach. Chrietensen has indicated that
•
LP. 339] .