Interspecific and intraspecific otolith variability in the genus Merluccius as determined by image analysis

Morphological variation in the sagittal otoliths of six species of the genus Merluccius was compared. The outlines of the otoliths were broken down numerically and classified according to numerical taxonomic methods. The results of this classification indicated that the specific characters of the sagittae emerge with individual growth, so that the otoliths from small individuals of various species exhibit plesiomorphic characters and are quite similar to one another. The otoliths from individuals longer than 20 cm can be classified into two geographic and phylogenetic groups: a Euro-African group (M. merluccius, M. capensis, and M. paradoxus) with plesiomorphic features, and an American group (M. bilinearis, M. productus, and M. gayi).