Variation in body condition, fat content and growth rate of Icelandic summer-spawning herring Clupea harengus L.

Interannual variation in Fulton's condition factor ( K ), total body-fat content and growth rate were investigated for the Icelandic summer-spawning herring Clupea harengus over the period from 1963 to 1999. The results show a close relationship between K and the body-fat content in the autumn, both of which correlated to the growth rate in the same calendar year. A relationship was also found between K during the prespawning season (February to June) and K in the autumn (September to December) in the same year. The different measures of body condition were not found to be related to sea temperature or zooplankton indices, while the spawning stock biomass had negative effects on the fish condition. The results imply that the body condition in the autumn is representative of the feeding success over the whole foregoing year and is therefore related to the growth rate that year. The growth rate appears to be relatively uniform throughout the year.