Shape Analysis of Otoliths of the Round goby, Neogobius melanostomus (Gobiiformes, Gobiidae), from the Black Sea Basin

The aim of this study was to assess the discriminability of the stocks of the round goby Neogobius melanostomus based on the shape of its otoliths. Recent otolith-shape-based species and stock discrimination studies were using otolith contours in sagittal plane and we are following this approach. We hypothesized the possibility of existence of several geographically separated populations of the round goby. Round gobies have been sampled from different locations of the North-Western Black Sea, otoliths were removed in course of the full biological analysis and photographed in sagittal plane. Principal components of the otolith contour were processed by linear discriminant analysis aiming to cross-validate the discriminability of round gobies placed at different geographical locations. This would allow demonstration of different stocks or populations. This research allows to conclude the limited applicability of otolith contours for discrimination of stocks or populations of round goby based on multiple annual samples. However, neither classification matrices of discriminant analysis nor cluster analysis dendrograms showed a single pattern except for the high year to year otoliths variability. This allows to hypothesise a strong response of contour formation to habitat and feeding conditions. However, this assumption needs to be verified by further studies.