Migration of cod (Gadus morhua): tagging experiments at the Faroes 1952-1965: Merkingarroyndir við føroyskum toski 1952-1965

Abstract

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.