Biologien til torsk (Gadus Morhua) i Oslofjorden, med hovedvekt på kondisjon og vekst

• Main Author: Fagerli, Camilla
• Other Authors: Karl Inne Ugland
• Format: Master Thesis
• Language: Norwegian Bokmål
• Published: 2007
• Subjects: marin biologi limnologi; VDP::480; Gadus morhua
• Online Access: http://hdl.handle.net/10852/11646; http://urn.nb.no/URN:NBN:no-14497

Abstract (in English) Cod (Gadus morhua) was collected with bottom trawl from six different sites in the Oslofjord during autumn, winter 2004 and spring, summer 2005. The condition factor, Fultons K, was calculated from the recorded length and weight, while subsamples of the liver were used for determination of the percentage of fat in the liver and for measuring the hepatosomatic index (HSI). Age was determined from otoliths, and the growth pattern was estimated from its length and age. The stomach content was analyzed by Rune R. Hansen and Martin Malmstrøm as part of their investigation on distribution of parasites. This gave an indication of diet. The condition status of the cod, measured by Fultons K, HSI and percentage of fat in the liver, were compared in order to find difference between locations and seasons. There was variation in condition between the different sites and through the year. The seasonally variation of the condition, measured by the three indexes, appeared in some sense to follow the same pattern. Best condition was recorded from the winter while it appeared to be very low after spawning. The cod in the Oslofjord seem to be in poor condition compared with free living cod form other locations.