EFFECT OF PARENT TYPE AND TEMPERATURE ON VERTEBRAE NUMBER IN JUVENILECOD, GADUS-MORHUA (L), IN NORTHERN NORWAY

Cod juveniles settling in shallow water and recruiting to coastal cod (CC) stocks have lower vertebrae number than juveniles settling in dee p water and recruiting to Northeast Arctic cod (NAC) stock. We investi gated whether the differences in vertebrae number in CC and NAC were c aused by genetic differences or by exposure to different temperatures during the embryonic period when the vertebrae number is determined. E gg groups from NAC and CC parents (parent groups), and egg groups from CC broodstocks (broodstock groups) were maintained at constant temper ature during the egg stage and reared to the juvenile stage before the ir vertebrae were counted. Data on vertebrae number from year classes of CC and NAC were compared with the experimental results. The vertebr ae number of the male parents had a greater influence on the vertebrae number of the offspring than the vertebrae number of the female paren ts, indicating that the parental effect was a genetic sex linked effec t. NAC parents produced offspring with higher vertebrae counts than CC parents. There was an inverse relationship between temperature and ve rtebrae counts in the broodstock groups, but no correlation between av erage vertebrae number (AV) and expected temperature during the spawni ng period in Lofoten for the NAC year classes. Our experiments show th at the differences in vertebrae number between coastal cod and Northea st Arctic cod are, at least in part, genetically determined.