Biologien til hyse (Melanogrammus aeglefinus) i Oslofjorden : med hovedvekt på kondisjon og vekst

Abstract

Abstract Haddock (Melanogrammus aeglefinus) was collected from five sites in the Oslofjord. They were collected during the fall 2004, spring and summer 2005, by trawling. The fish were weighed and measured for length. Subsamples were frozen and taken back to the laboratory for analyses of the percentage of fat in the liver, and measuring heptosomatic index (HSI). The contents of the stomachs were analysed as part of investigations on the distribution of parasites in fish in the Oslofjord. The age of the fish was determined by the use of otholiths. The different measurements of condition (Fulton s K, HSI and percentage of fat in the liver) were compared for different seasons and different locations. There are large variations in the condition, but they seem mostly related to wintertime and spawning. The condition indices HSI and percentage of fat in the liver were closely related. Fulton s K on the other hand was poorly related to HSI and contents of fat in the liver. The haddock in the Oslofjord seem to be at good condition, and follow the same patterns of variation as reported from other places. We caught very few haddock in the inner part of the fjord, and according to an experienced local fisher, the haddock appears in large quantities in the inner fjord during January and February.