Ársrit Fiskifélags Íslands - 01.01.1933, Síða 76

74
ring were investigated and table 39 shows how the material was
divided between the different places in this part of the country,
and between the different periods into which the herring season
is divided. Hence in the tables, Aug. 1 denotes from the lst to
the lOth, Aug. 2 the llth to the 20th, Aug. 3 the 21st to the
31 st etc. The average length of the mature (30 cm. -f-) herring was
35.27 cm. As the season advanced the herring grew gradually bigger
(table 40). In table 41 the herring is divided into three classes
according to size, so that one class contains all the herring under
35 cm., another the herring of 35 cm. (35—35.9), and the third all the
herring above 35 cm. The medium sized herring (20—29 cm.) were in
greater quantity than usual: — from 0—2.2 °/0 of the total number
(table 42). 75 °/0 of the medium sized herring were two years old,
22 °/0 three years old and 3 °/0 four years old.
A great deal of herring were weighed and measured to find
k for the herring of this place and this time, according to the
l3 100 g
formula: g = k • -jqq- or p For the mature herring k
proved to be 0.77—0.80 and the smaller the herring were, the
greater k (table 44), but for the medium sized 0.79—0.93 (table
45). Unfortunately there was no time then to determine whether
/c stood in direct relation to the fat.
Then about 2000 stomachs of herring from different places
and caught at different times were investigated. The stomachs
were taken out immediately after the landing of the herring, 10—
20 being taken from each catch. Then the content of each sto-
mach was measured (in ccm.) by displacement (Jespersen 1932,
p. 6), and the mean worked out. At last the average con-
tent was determined (ccm. per stomach) for each place (cf. above)
and each time (Aug. 1 etc.).
The result of these investigations is shown in table 46 at the
top of which (1) is shown the total stomach content, then the
copepoda separately (2), and at the bottom the euphausids (3).
The method which has been used to determine the proportion
between copepods and euphausids will not be outlined here,
as I intend to discuss it in another paper. And yet it must be
mentioned that I have used methods rather different to Jesper-
sen’s (Jespersen 1932, pp. 15—16), and I have only dealt with
the two main groups of the planktonic crustaceans which consti-
tute by far the most important part of the food of the herring.
And for the rest I refer you to the figure on p. 58 which is
based on the table.