Náttúrufræðingurinn - 1953, Blaðsíða 47

LAXAMERKINGAR 1947—51
187
one smolt was recovered five days after being tagged. It had been eaten by a cod,
which was caught about five kilometers from the estuary of the river Olfarsá. For
further information about the marking and tagging of smolts see table I.
Kelts were tagged in several rivers (see table II). During 1948 through 1951
459 kelts were tagged in the river Elliðaár and 43 (9,4%) were recovered. On the
river Elliðaár there is a power dam, which the salmon can not pass. The salmon
are caught in a trap below the power station and are lorried up above the dam.
More than two thirds of the recoveries are made in the trap and by seining the
river below the trap for securing salmon for hatchery purposes. In 1948—49 tagged
kelts from the river Elliðaár were released into the river Flókadalsá in the district
of Borgarfjördur on the west coast. The following year five (10,2%) salmon re-
turned to the parent stream, the Elliðaár. In 1949 28 kelts from the river Elliðaár
were again released in the river Flókadalsá, but no recaptures were made this time.
In 1948 64 kelts were tagged from three rivers in the district of Borgarfjördur.
Five (7,8%) recaptures were made. In 1948 55 kelts were tagged from the river
Stóra-Laxá, a tributary to the river Ölfusá-Hvítá on the south coast. Seven (12,7%)
recaptures were made. In 1950 96 kelts were tagged and four (4,2%) were recap-
tured. In 1948 25 kelts were tagged in the river Sog, another tributary to the river
Ölfusá-FIvítá, but no recaptures were reported.
The length of the smolts in the river Olfarsá at the time of down stream mi-
gration was 10—15 cm (fork length). After a year in the sea 19 marked salmon
were 57,2 cm on the average and their average weight was 2 kilogramms. The
average length increment of 28 kelts from the river Elliðaár after a year’s stay in
the sea was 7,9 cm, but varying from year to year. One kelt that stayed two years
in the sea increased 18 cm in length.
Out of the 47 recaptures from the smolt markings in the river Olfarsá, all but
two (4,3%) were recovered in the parent stream. A similar result was had from
the tagging of kelts in the river Elliðaár; 43 recoveries were made, and all but two
(5,1%) in their home stream.