Fróðskaparrit - 01.01.2005, Blaðsíða 125

MERKINGARROYNDIR VIÐ FØROYSKUM TOSKI 1952-1965
123
ence between years is an artefact), but
there are no data available to confirm this
hypothesis. On the other hand, the actual
migration pattern may have differed be-
tween years. Tagging experiments during
1997-2004 indicate that cod may some
years migrate into shallow water close to
land when food abundance on the typi-
cal fishing grounds is low (unpubl.). We
are, however, not able to decide whether
this may have happened during the period
1952-1957 (that was selected for the ana-
lysis).
The general linear model also indicated
that time of the year (season) may play a
role (although p>0.05). We investigated
the material in Strubberg (1916), i.e. the
appendix with inforination on individual
recaptured fish, in the same way as in this
study. It indicated a clear effect of season.
It is not surprising, because a number of
factors, e.g. food availability (unpublished
material), vary on a seasonal basis (Rae,
1967). Tagging experiments on the south-
ern coast of Norway have also shown an
effect of season: juvenile cod in those ar-
eas migrate to deep water (about 75 m)
during summer (Danielssen and Gjøsæter,
1994).
Cod moving long distances
Only three out of about 1000 cod were
caught outside Faroese waters (i.e. Faroe
Plateau and Faroe Bank). Previous tag-
ging experiments have also shown that
such highly migrating cod are extremely
scarce. When considering all recaptured
cod in Strubberg (1916; 1933) and Táning
(1940), only one out of about 2100 cod was
recaptured outside Faroese waters (in the
Barents Sea). Tagging experiments during
1997-2004 have also indicated a very Iow
frequency (about 5 of 6000). These cod
were recaptured in Shetland waters (one
specimen), off the coast of Norway - close
to Trondheim - (two specimens) and in
the Barents Sea (two specimens). Thus
- when including this study - cod from
Faroese waters have been recaptured in the
whole area from Iceland, North Sea to the
Barents Sea.
It is also very seldom observed that
cod migrate to Faroese waters from dis-
tant areas. Icelandic tagging experiments
during 1948-1986 showed that only four
out of about 11000 recaptured cod were
recaptured in Faroese waters (Jónsson,
1996). It should be mentioned, however,
that tagging experiments indicate that cod
on the Faroe-Icelandic ridge are mainly,
or at least partially, of Icelandic origin
(unpubl.). Immigration of cod from the
areas north of Scotland/Shetland is also on
a very low level since no cod out of 430
recaptured cod came from Faroese waters
during the late 1970s (Easey, 1987).
Implications for fisheries management
The fact that cod move to deeper waters
when they grow larger, and that they tend
to stay in the same main area has impor-
tant implications fbr fisheries manage-
inent. The fishing inortality has been high
in recent years (ICES, 2004). If the fishing
mortality should be reduced by introduc-
ing new closed areas, they should be lo-
cated close to land if the young fish should
be protected. If the adult fish should be