Íslenskar landbúnaðarrannsóknir - 01.09.1978, Page 82

80 ÍSLENZKAR LANDBÚNAÐARRANNSÓKNIR
TABLE 1.
Experimental design of 1974 and 1975 tagging experiment regarding calibration of Carlin tags and tag loss.
1974 experiment
Fork length (cm)
Type of tag Type of smolt 9.5—14.5 13.6—16.5 16.6—19.5
Carlin1) 2-year-outdoor 500 2X5002) 2X500
1 2-year-outdoor 2X500 2X1000 2X500
Microtag ■4 2-year-photoperiod 2X550 2X950 78
1 1-year-photoperiod 2X500 2X1000
Microtag & ventral 2-year-outdoor 2x500 L.V. 2X1000 R.V. 2X500 R.V.
Carlin & microtag 2-year-outdoor 843
Plastic & microtag 2-year-outdoor 1000
1975 experiment
Fork length (cm)
Type of tag Type of smolt 9.5—11.9 12.0—14.4 14.5—17.0
Carlin1) 2-year-outdoor 800 800 800
Microtag /2-year-outdoor 2X400 2X400 2X400
*- 1-year-photoperiod 2X400 2X400
Carlin & microtag 2-year-outdoor 400 400 400
*) Carlin tags were divided into replicates of odd and even tag numbers.
2) 2X500 means two replicates of 500 each; in one replicate, all fish bear the same microtag code.
rotagging operation. In 1975 the tagging
was performed entirely by Icelandic per-
sonnel under the supervision of the au-
thors. After tagging, the smolts were all
dipped into a 1:6000 solution of malachite
green to retard fungus due to handling
and were transferred to an outdoor hold-
ing pond.
The detailed experimental designs and
the numbers tagged in each group are
shown for both years in Table 1. Length is
used as a major variable because evidence
exists (Ísaksson, 1976) that dangler-tag
effects are more extreme on small fish. In
the 1974 experiment, the two smaller
length groupings overlap because sorting
was done primarily with a mechanical
bar-grader, but in the 1975 experiment,
hand-sorting was performed to make the
groups more exact.
All microtag groups contained two or
more replicates. Replicates are groups of
like tag codes formed by dividing each lot
of fish into sublots as they were tagged.
Carlin tag groups were assigned to repli-
cates on the basis of tag numbers (e. g.,
odd numbers are one replicate, even
numbers another).
The principal measure ofCarlin tag loss
was based on the double tagging using
microtags as shown in Table 2. Ventral
fins were removed on some microtagged