Ontogenetic spatial dynamics of the deep-sea teleost Aphanopus carbo in the NE Atlantic according to otolith geochemistry

The spatial distribution of deep-sea fishes is commonly related to major water masses or regional circulatory features that in turn may reflect differences in food-web structure and productivity. Aphanopus carbo is a benthopelagic species that undergoes horizontal and vertical migrations driven by spawning and by feeding, and for which a large-scale clockwise migration around the NE Atlantic is hypothesized. In this work, the adequacy of otolith microchemical composition used as tool to discriminate A. carbo specimens caught at different areas was investigated. Furthermore, potential birth areas and spatial pattern migration throughout the species life cycle were studied. Trace element concentration (TEC) in the otolith edge allowed the discrimination of the locations where specimens were caught and supported the separation between the northern and the southern distribution areas. The existence of two natal sources was suggested based on the separation of otolith core TEC into two groups. Longitudinal multivariate analyses applied to TEC data also sustained the separation of the otoliths into two main groups, but the mixing between them gives support to the species migratory hypothesis. The acceptance of both southern and northern spawning grounds and of migratory movements along the NE Atlantic in both northward and southward directions implies changes to the current migratory hypothesis that might be translated into new definitions of A. carbo stock structure and therefore fisheries management.