Speci¢c Merluccius otolith growth patterns related to phylogenetics and environmental factors

A comparative morphological study was performed on the otolith growth patterns of 11 species of the genus Merluccius. The otolith growth pattern, based on the radius of the ¢rst eight growth increments (GI) from the otolith core, was determined from transverse sections of sagitta otoliths.The structure and periodicity of the GI were identi¢ed based on previous knowledge. Two cluster analyses were performed using GI width as a proxy for otolith growth. The ¢rst cluster analysis corresponded to the juvenile (immature) period of the ¢sh including the mean width of the ¢rst four GI. The second analysis compared the mean width of the next four GI, i.e. those corresponding to mature ¢sh. The results showed an important environmental in£uence in immature ¢sh; while after maturation, the GI pattern was also related to an endogenous in£uence depending on the phylogenetic line.