Ársrit Fiskifélags Íslands - 01.01.1933, Blaðsíða 77

75
The content in the purse seine herring was on the average
.•as follows: The smallest 3.7 and the largest 9.2 ccm. per stomach,
<it each period. In the drift-net herring there was as usual (Jes-
persen 1932, table 2) much less, on the average mostly 1—2 ccm.
per stomach (table 46 and figure 14 refer to purse seine herring,
Ibut table 47 deals with the stomach content of drift-net herring).
When everything was taken into consideration, the stomach con-
tent of drift-net herring only amounted to about 28 °/ö of the sto-
anach content of the purse seine herring (table 48).
Jespersen shows there is a connection between the quantity
-of the catch (in barrels) and the quantity of food in the herring
'(Jespersen 1932, fig. 5). With regard to this I have made some
linvestigations (v. fig. 15, p. 61). It is apparent that the size of
the catch increases in proportion to the quantity of the food
'(v. also table 49). On the other hand there are many exceptions
•and this is probably due to the fact that herring feeds especially
at certain times of the day. In table 50 there is a summary of
the amount of food in herring from the same time and place,
according to the different hours of the day, and it is most appa-
rent at 9 o’clock and 18—21 (cf. Jespersen, 1928). In the table the
quantity of food is shown both in ccm. per stomach and in per-
•centage of the average quantity of food for the whole 24 hours.
The surface temperature was taken in many places to find
out if there was a possible connection between the quantity
of food, on the one hand, and the temperature on the other.
From about the 20th of July until about the 20th of August the
greatest amount of food existed where the temperature was about
•8.2 C., but after that maxima began to appear at different tem-
peratures, but on the other hand both the food and the catch
moved about more, staying a shorter time in each place.
III. The other investigations. Material collected from cod
•caught at the Vestmanna Islands on the 2nd to the 3rd of May was
used to compare the efficiency of the two kind of fishing-gears used,
net and longline. In the column »lóð« in table 52 the result of the
measurements of longline cod is to be found, but in the column
»net« the length-distribution of net-caught fish is shown. Suppos-
ing the longline can take an proportionally equal quantity of
íish of all sizes, and does not concentrate on any special size,
then the size of the longline-fish is representative of the size of
the fish in the sea.
All the fish taken quantitatively by nets are of a certain
•size, and fish of a smaller and a larger size escape more or less