Íslenskar landbúnaðarrannsóknir - 01.09.1976, Síða 19

TAGGING EXPERIMENTS AT KOLLAFJÖRÐUR 17
1.4 untagged salmon return for each tagged
salmon. This is the lowest ratio ever obtained
at the Fish Farm indicating very successful
tagging and/or very little tag loss. It should
be noted that all fish tagged in these experi-
ments were over 13,5 cm in fork length. The
results are thus only representative of smolts
in that size category. The remrn rate of one-
year-smolts to the Fish Farm is averaging
8.5 % which is 4 times better than the return
rate of one-year-smolts in 1973 (ÍSAKSSON
1976) which was the best on record at the
Fish Farm up to that point.
Group 12 consists of various smolts that
were put into a floating pen on a saltwater
lagoon in the spring of 1973 for salinity
tolerance experiments. The fish were tagged
in October when they were released and
their sensitivity at that stage may be partly
responsible for the inferior remrn rate in
that group. This experiment will be discussed
in detail in a later report.
The amount of straying in all groups com-
bined was only 2,4% which is very close to
the straying in 1973 (Ísaksson 1976) but
lower than in earlier experiments (Guð-
jónsson 1970).
ÍSLENZKT YFIRLIT
Niðurstöður merkingatilrauna 1973 í
Laxeldisstöðinni í Kollafirði.
Árni Ísaksson
Veiðimálastofnunin,
Reykjavík.
Rætt er um bráðabirgðaniðurstöður merk-
ingatilraunanna 1973 í Laxeldisstöðinni í
Kollafirði. Gönguseiðin voru annaðhvort
3. The total run.
The total run to the Fish Farm was 3065
fish. Estimates indicate that 2850 of these
were remrning as grilse. About 1186 of these
were marked in some way out of 11.100
released, giving a remrn rate of 10,7% for
tagged and finclipped fish. The number re-
mrning unmarked was about 1660. The total
release of unmarked smolts was 11,800. This
gives about 14% remrn rate of unmarked
fish which is in close agreement with the
remrn rate for adipose clipped fish dicussed
earlier.
The total number of fish released in 1973
was 23.300. Using the number of grilse re-
turning we get a 12,2% return rate for all
fish released in 1973.
A total of 328 kelts were tagged and re-
leased in December of 1973. The day after
their release very cold weather started with
several degrees of frost which lasted for se-
veral days. A thick icesheet was formed on
the Kollafjörður inlet and undercooling of
the sea water was observed. It was expected
that these adverse conditions might reduce
the return rate of the kelts. The observed
return rate for these was 1,2% as compared
to 30% for 1973.
veiðiuggaklippt eða merkt með Carlin-merkj-
um. Merkin vom tvenns konar, annars vegar
plastmerki, fest með plastþræði, hins vegar
venjuleg sænsk merki, fest með stálvír. Helzm
niðurstöður eru sem hér segir:
1. Endurheimta eins og tveggja ára göngu-
seiða, sem fengið höfðu eðlilega birtu-
breytingu í 35 vikur fyrir sleppingu, var
svipuð, nálega 8—10%.
2. Endurheimta merkja, sem fest voru með