Íslenskar landbúnaðarrannsóknir - 01.09.1978, Blaðsíða 106

104 ÍSLENZK.AR LANDBÚNAÐARRANNSÓKNIR
The 2-year smolts were put in the re-
lease pond on May 13 and fed dry feed,
using an automatic feeder run oíf a car
battery. On May 29, the release pond was
opened and feeding was discontinued. On
the same day, the smolts for the direct
plant were transported to the stream and
released in the vicinity of the pond.
It was observed that the outmigration
from the pond was slow. On June 6 it was
estimated that 600 smolts were left in the
pond. On July 4, some 300 smolts still
seemed to be in the pond, at which time a
seine was used to empty the pond.
The recovery
In the early summer of 1976, a trap was
built just above the release pond at Ar-
túnsá. This was a conventional wooden
trap with on adjacent weir preventing the
upstream migration ofsalmon.
The first salmon were seen entering the
river about mid-July and were soon
caught in the trap. About mid-August
when 30 salmon had entered the trap, it
started to rain heavily and within 2 days
the trap was washed out. It was consi-
dered impractical to fix it, and on August
20 the river was leased to a group of sports
fishermen for fishing. The fishermen were
required to bring each salmon caught to
the fishing hut at Ellidaár for tag retrieval
and measurement of the fish. This worked
out fairly well, although in some in-
stances, fishermen did not report their
catch. Approximately 55 salmon were
caught on rods. At the end of the fishing
season on September 20, the river was
seined for capture of the remaining sal-
mon. It is believed that no more than ab-
out 15 salmon were left in the stream.
A considerable amount of untagged
salmon was caught in the river. These
salmon were probably from two sources:
firstly, they could be the results of smolt
plants in 1974 by the owner of the river;
secondly, they could be the salmon re-
leased at Kollafjördur which had strayed
considerably to Artúnsá as well as to other
rivers in the vicinity of the Fish Farm.
Survival
The results are shown in Table 1 and Fig.
2. It is evident from the graph and cor-
roborated by ax2 test (0.05 level) that the
survival of the smolts kept in a release
pond is much superior to that of the smolts
planted directly. From Table 1 we see
further that the average size of these
smolts is only 13.5 cm at tagging. Ac-
cording to Isaksson and Bergman (1978)
the mean survival for similar smolts re-
leased at Kollaíjördur in May 1975 lies
around 1%. Compared to smolts released
in June, as well as those released in May in
other years, this percentage is very low.
Since the returns to Artúnsá were well
over 1.5%, it seems that the experiment at
Artúnsá has been a considerable success
and would probably give reasonable re-
turns from pond releases with better
smolts and improved release timing.
It should be kept in mind that the survi-
val figures in Fig. 2 are total returns and
include the straying of salmon to other
rivers. Considerable straying of smolts
from Ártúnsá to the rearing home at Kol-
lafjördur can thus greatly affect the feasi-
bility of the operation at Ártúnsá.
Straying
The straying ofsalmon smolts released at
Ártúnsá to other rivers and Kollafjördur
Fish Farm in particular can be seen in