Íslenskar landbúnaðarrannsóknir - 01.09.1978, Page 69

ÍSL. LANDBÚN.
J. AGR. RES. ICEL. 1978 10,2: 67-73
A data file for marked salmon smolt
releases and adult returns
Geir r. jóhannesson
and
Mar;anna Alexandersdóttir
Institute of Freshwater Fisheries, Reykjavík.
ABSTRACT
A program has been written to handle release data of tagged smolts and the returns ofadults. It is written in
FORTRAN IV for processing on IBM 360/30. The program is flexible and allows for casy expansions or
modifications. Examples of printouts are provided.
INTRODUCTION
The success of a hatchery operation can be
measured effectively by the marking of
smolts and other young fish released from
the hatchery production and by recoveries
of returning adults. Such experiments
have been in progress at the Kollafjördur
Fish Farm since 1965. The initial marking
methods were fm clipping and marking
with Carlin tags. In 1974 the *microtagg-
ing technique was introduced at the fish
farm and it was used in conjunction with
Carlin tags.
When evaluating results from marking
experiments, we make various assump-
tions. One assumption is that the marking
does not affect the fish. Another is that
there is no loss of the mark. The mic-
rotagging technique largely meets these
criteria. A third assumption is that the
ocean environment is constant, and survi-
val of different age, length and treatment
groups can be evaluted by marking ex-
periments. However, it is becoming
equally clear that ocean survival varies
from year to year and that this must be
considered in each evaluation.
Ultimately, one must consider a n-di-
mensional space containing many prim-
ary factors and their interactions, which
can only be done by considering large and
diversified material. But the evaluation of
large-scale release experiments is inti-
mately tied to a computerized system. In
1974—75 such a data file system was de-
signed for storing and evaluating data
gathered on tagging, releases, and returns
at Kollafjördur. This program was writ-
ten by Jóhannesson and later modified by