Investigation of otolith mass asymmetry in three stocks of European sardine, Sardina pilchardus (Walbaum, 1792) from Türkiye

It was aimed to investigate sagittal otolith mass asymmetry Sardina pilchardus sampled from Aegean, Marmara and Mediterranean seas of Türkiye in present study. In this study, differences between right and left otoliths were statistically significant for Marmara and Mediterranean seas (P<0.05) not significant for Aegean Sea, (P˃0.05). The mean values of otolith mass asymmetry (X) were found between 0.0393 and 0.0144 according to Aegean Sea, Marmara Sea and Mediterranean Sea, respectively. In addition, absolute mass asymmetry │X│ were calculated as 0.03226±0.00514, 0.02057±0.00439 and, 0.05141±0.00755 for S. pilchardus samples according to Aegean Sea, Marmara Sea and Mediterranean Sea, respectively. The present study showed that the otolith mass asymmetry in S.pilchardus does not depend on fish length and otolith growth. Also, when there were no significant differences between localities for otolith mass asymmetry (P˃0.05), there were significant differences for absolute otolith mass (P˂0.05). The value of the otolith mass asymmetry can reveal information about pollutants such heavy metals, pesticides, stressors, and changes in the physico-chemical characteristics of water in relation to the environment of fishes. This is the first study about otolith mass in three stocks of S. pilchardus (Walbaum, 1792) from Türkiye.