Íslenskar landbúnaðarrannsóknir - 01.09.1976, Page 8

6 ÍSLENZKAR LANDBÚNAÐARRANNSÓKNIR
Table 3
Recapture Rafes for Various Lengfh Groups
of Two-Year-Old Smolts Tagged in 1971
Fork length Number Number Percent
cm tagged recaptured return
14.0 (13.6-14.5) 1184 31 .. - - . 2.6 .
15.0 (14.6-15.5) 1354 55 4.1
16.0 (15.6-16.5) 681 27 4.0
17.0 (16.6-17.5) 159 13 8.2
18.0 (17.6-18.5) 58 6 10.3
Groups 1 and 3 are the Carlin tagged one-
year-old smolts. The combined returns from
these groups are 0,32%. These are low re-
mrns, but 30 times better than the returns
from one-year-olds tagged in 1970. These
results indicated that slow progress was being
made.
As in the electric fishing, the returns of the
control two-year-olds were similar as for the
one-year-olds amounting to 0,5%, which
demonstrated further that the age of the
fish was not as important as correct treatment
of the fish, with respect to seaward migration
and adult returns. No fish returned from a
group of fin-clipped two-year-olds that were
kept indoors until the day of their release.
Returns from group 2 were somewhat
lower than the corresponding remrns of
Carlin tagged one-year-old smolts. This is
to some extent due to the fact that the re-
turns of these fish in 1973 as two-year-old
adults could not be considered valid. The
reason for this was the great electric fishing
of these fish in 1971 and their re-release in
1972, which means that many of the adipose
clipped fish remrning in 1973 were only one-
year-old adults.
The total returns from the release of
tagged two-year-smolts in 1971 is 4,6%. Of
these about 87% returned in 1972 and 13%
in 1973 after two years in the sea. This is in
close agreement with previous findings at the
Fish Farm. There did not seem to be appre-
ciable difference between those tagged early
(group 6) and those tagged late (group 7).
The straying of salmon to other rivers
amounting to 4,9% is not substantial com-
pared to a 17% average for 1967—69 pre-
sented by Guðjónsson (1970).*
* It should be pointed out that straying in this
and following reports is measured by the abso-
lute recovery of tagged salmon outside the Fish
Farm. No adjustment is made for salmon left
to spawn or those not reported.