Fróðskaparrit - 01.01.2005, Page 102

Migration of cod (Gadus morhua): tagging
experiments at the Faroes 1952-1965
Merkingarroyndir við føroyskum toski 1952-1965
Jákup Sverri Joensen1, Petur Steingrund2, Arnold Henriksen3 and Rógvi Mouritsen4
1 Former director of Faroese Fisheries Laboratory (retired).
2 Corresponding author. Email: peturs@frs.fo
2A Faroese Fisheries Laboratory, Nóatún, FO-IOO Tórshavn, Faroe Islands.
Úrtak
í tíðarskeiðinum 1952-65 vórðu tilsamans 6512
toskar (í miðal 50,7 cm langir) merktir á føroyska
landgrunninum. Tilsamans 1043 toskar (í miðal 59,1
cm langir) vórðu fiskaðir aftur (16%), ofta longu tað
fyrsta árið eftir merking. Úrslitini vístu, at toskur av
øllum landgrunninum savnaðist á Norðhavinum at
gýta, og toskur av økinum vestan fyri Sandoy/Suðuroy,
umframt Norðhavinum, eisini fór í Vágahavið at
gýta. Tað tók toskinum ikki meira enn fáar vikur at
koma til ella frá gýtingarøkjunum. Ferðingin uttan
um gýtingartíðina var rættiliga avmarkað, og var ofta
minni enn 10 fjórðingar frá staðnum, har merkt varð.
Tað vóru tó altíð summir toskar, sum fóru til nýggj og
meira fjar øki á landgrunninum. Positivt samband var
millum ferða- og fiskilongd, og eisini var ferðalongdin
ymisk fyri merkingarøkini og hvat ár, sum merkt varð.
Sera sjáldan fóru toskar av føroyskum øki til onnur
havøki.
Abstract
During the period 1952-65, 6512 cod (on average 50.7
cm) were tagged on the Faroe Plateau. In total 1043
cod (on average 59.1 cm) were recaptured (16%), often
during the first year after tagging. The results showed
that cod from all areas of the Faroe Plateau aggregated on
the main northerly located spawning site “Norðhavið”
whereas cod south-west of Faroe Islands, in addition to
“Norðhavið”, also migrated to a spawning area located
west of Faroe Islands (“Vágahavið”). The duration of
the spawning migration to or from the spawning areas
only lasted a few weeks. The migration, that was not
associated with spawning was quite limited, often less
than 10 nautical miles from the tagging locality. There
were, however, some fish, that moved to new and
distant areas on the Faroe Plateau. Migration distance
was positively correlated with fish length and varied
between tagging areas and years. Extremely few cod
moved out of Faroese waters.
Introduction
Knowing the migration pattern of fish
populations and fish stocks is a basic
requirement in many respects. In com-
mercial fishing, físhing is most profitable
when the físh are aggregated, e.g. during
the spawning season, and Faroese físh-
ing vessels have historically exploited the
valuable spawning places south of Iceland
(Táning, 1943). In ecology, the distribu-
Fróðskaparrit 53. bók 2005: 100-135