Otolith elemental signatures indicate population separation in deep-sea rockfish, Helicolenus dactylopterus and Pontinus kuhlii, from the Azores

Deep sea rockfish, Helicolenus dactylopterus and Pontinus kuhlii from the Azores archipelago were used to study population structuring using the trace element composition of the otolith. Through solution-based inductively coupled plasma mass spectrometry we identified elemental profiles that adequately identified fish from different island groups in the region (East, West and Central). Mg:Ca, Pb:Ca and Li:Ca ratios combined to distinguish H. dactylopterus with 67% overall success. Sr:Ca, Ba:Ca, Li:Ca and Cu:Ca provided adequate distinction in P. kuhlii with a mean jack-knifed classification success of 75%. This was a first attempt at determining the distinguishability of fish aggregations from this oceanic island setting, where suitable habitat for these species is limited and fragmented. Results of our study corroborate with previous research pointing to constrained home ranges for these species. Implications for fisheries management are important since these commercial resources should be managed locally rather than regionally.