Otolith shape in juvenile cod (Gadus morhua): Ontogenetic and environmental effects

The objectives of this study were to describe the otolith shape development of cod from post-metamorphosis larvae to juveniles and to examine whether shape development is an ontogenetically determined process. Fish were reared under three different temperature regimes and two feeding levels. I examined shape by the length~width relationship of the otolith as well as the number and size of the lobes formed. Otolith size and crenulation is exclusively linked to fish size, indicating an ontogenetically determined development. Otolith shape is closely associated with the spatial development of the lobes. This process is linked with food consumption. Higher food consumption leads to a higher number of larger lobes, resulting in a more rectangular otolith. In conclusion: Otolith shape development consists of an ontogenetic component in the form of increasing size and crenulation and an environmental component impacting on the size and number of the lobes formed.