Preliminary results of otolith elemental composition analysis of Dissostichus spp. in Subarea 48.2

In order to explore aspects related to the structure of population units and habitat use of Dissostichus spp. within CCAMLR Subarea 48.2, the elemental composition of nuclear and marginal sections of 10 otoliths from adults of D. eleginoides and 20 otoliths from adults of D. mawsoni from samples of otoliths collected during the first season of the research carried out by the Chilean Delegation in Subarea 48.2 of CCAMLR during the 2015/16 fishing season. The otoliths through laser ablation and mass spectrometry with inductively coupled plasma (LA-ICPMS) was sampled and analyzed. Eleven elements were selected for analysis: 7Li, 23Na, 24Mg, 52Cr, 55Mn, 59Co, 60Ni, 63Cu, 86Sr, 120Sn y 138Ba, using their relative concentration to Ca. The univariate and multivariate analysis of the elemental composition of the nuclear zone showed significant differences between species, suggesting physiological differences and/or segregation of nursery habitats between them. The analysis of the elemental composition of the marginal sections presented univariate differences but not multivariate differences between species, suggesting a higher degree of overlap between the habitats used by the adults of each one of them. The differences found between nuclear and marginal sections among the species were consistent with the change of habitats described in the literature for each one of them. The comparison of our results with previous reports of elemental composition showed similarity between D. eleginoides samples of this study and the samples previously collected in South Georgia and Shag Rocks. In the case of D. mawsoni, the results clear differ from the results available for the Ross Sea, suggesting the existence of different demographic and/or evolutionary units in each area.