Size of spawning Arcto-Norwegian cod (Gadus morhua L.) and the effects on their eggs and early larvae

Abstract

Using a new method for determining the stage of spawning in batch spawners, a positive correlation between the length of Arcto-Norwegian cod females, having spawned 25-75% of their eggs, and the egg diameter was established. This was not found in 1992 when egg groups from cod females in all stages of spawning were used. The maternal effect of cod female size was compared to the effect of stage of spawning. This comparison revealed the following tentative conclusions: 1) The egg diameter is less affected by the length of the cod female than by its stage of spawning. 2) The fertilization percentage and larval activity are correlated with the stage of spawning of the cod female, but not to its length. The present results indicate that the maternal effect of individual changes in egg characteristics during spawning is larger than the maternal effect of cod female size. In addition investigations on egg mortality, larval feeding ability, genetics, bacteriology, biochemistry and rearing of selected larvae groups to metamorphosis were carried out. The project will be terminated in 1994.