Íslenskar landbúnaðarrannsóknir - 01.09.1976, Blaðsíða 16

ÍSL. LANDBÚN.
J. AGR. RES. ICEL.
1976 8,1-2: 14-18
Preliminary Results from the 1973
Tagging Experiments at the Kollafjörður
Experimental Fish Farm
Árni Ísaksson
lnstitute of Freshwater Fisheries,
Reykjavík, lceland.
ABSTRACT
The preliminary results from the 1973 Tagging Experiment at Kollafjörður Fish Farm are dis-
cussed. The smolts were either adipose clipped or tagged with Carlin tags. The tags were either
attached with polyethylene thread or steel wire. The primary findings are as follows:
1. One-year and tvo-year smolts released after 35 weeks of normal photoperiod had comparable
returns of 8—10%.
2. Carlin tags attached with polyethylene thread gave results which seemed not significantly dif-
ferent from those of tags attached with steel wire.
3. Cold brands applied to the side of the salmon-smolts were poorly visible on the returning adults.
4. One-year-smolts subjected to exercise gave no better returns than control.
5. Salmon fed a fatty dry diet had lower return rate than those fed with regular dry feed.
6. The return rate for unmarked salmon was close to 14% which was the same as the return rate
for adipose clipped fish.
7. The total run in 1974 was 3065 salmon of which approximately 2850 were returning as
grilse.
Introduction.
The Kollafjörður Fish Farm is very well
suited for the release of hatchery smolts,
having an outflow directly into the sea and
complete control over the returning fish. The
downstream migrants have been tagged with
dangler type tags for many years and the re-
sults from these experiments are discussed by
Guðjónsson (1970) andísAKSSON (1976).
The following report is a summary of results
obtained during the summer of 1974 and
will be published in more detail at a later
date.
The Smolts Tagged.
Out of 12 lots of fish that were released
from the Fish Farm in 1973 there were 6
consisting of two-year-smolts; 5 lots of one-
year-smolts and 1 group of one and two-
year-smolts that were released in the middle
of October from a floating pen located on a