Fróðskaparrit - 01.01.2005, Side 122

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MIGRATION OF COD (GADUS MORHUA):
TAGGING EXPERIMENTS AT THE FAROES 1952-1965
m) in the vicinity of the tagging area when
they grew larger. A varying proportion of
immature fish migrated to new areas of
similar depth on the Faroe Plateau. Migra-
tion to other places than the Faroe Plateau
was very seldom observed. The migra-
tion pattern, that was not associated with
spawning, was dependent on area of tag-
ging, físh length and year.
Fishery induced biases
During the period of the tagging program,
there were changes in the Faroese fish-
ery limit (Nolsøe, 1963; 1965). During
the period 1952-1955, the Faroese fish-
ery limit was 3 nautical miles from land.
In 1955, it was extended in some areas
west of Faroe Islands. It was extended in
1959 to 12 nautical miles, except for Brit-
ish fishermen who were allowed to fish 6
nautical miles from land. The spawning
area “Norðhavið” was closed to all gears,
except longlines and handlines. In 1964,
the fishing limit was extended to 12 nauti-
cal miles, measured from straight base-
lines. Foreign fleets (i.e. English, Scottish
and a few German trawlers) formally op-
erated outside the fishery limit. Inside the
fishery limit, the fishery was dominated
by small Faroese boats or cutters. The
larger Faroese vessels usually operated in
Icelandic or Greenlandic waters, but occa-
sionally in Faroese waters. Thus many of
the small cod were recaptured by Faroese
fishermen and the larger cod by English or
Scottish fishermen, e.g. on the spawning
grounds “Norðhavið” and “Vágahavið”
(Jákupsstovu and Reinert, 1994).
We expect that the results are biased
towards small fish caught by Faroese fish-
ermen operating inside the fishery limit,
as seems to be the case for the tagging
experiments conducted during 1909-13
and published in Strubberg (1916). Taken
into account the aggregations of spawning
cod in the “Norðhavið” and “Vágahavið”
(Táning, 1940; Jákupsstovu and Reinert,
1994) during March-April, it is notewor-
thy, that so few cod were recaptured at
these places during spawning time.
A varying fishing effort by area (/'.<?•
some areas are fished harder than others)
may have influenced the results. We do
not know how the fishing effort varied by
area, but it may have been highest where
it was possible to use small boats (e.g■
east of Nólsoy - ENO, Figure 5) or where
the trawlers dominated (e.g. east of the
Faroe Islands). The migration distance of
cod tagged in these fishery-intensive areas
may have been underestimated (too many
fish recaptured near the tagging locality)
whereas the migration distance may have
been overestimated for taggings in areas
with less fishing effort.
Spawning migration
There is no reason to believe that there
was any major difference in the spawn-
ing migration to and from the northern
spawning area “Norðhavið” compared to
the results in Táning (1940) even though
the westward migration from the spawn-
ing area was hard to see in the present
study. The material in this study was much
smaller and the fishing intensity in the ar-
eas west of “Norðhavið” may have been
less than in the east, as judged from Figure