Stock structure delineation using variation in otolith chemistry of snakehead, C hanna punctata (Bloch, 1793), from three Indian rivers

Summary Otolith chemistry was used to study the stock structure of C hanna punctata collected from the R iver G anga and its tributaries, the rivers Y amuna and G omti. Whole sagittal otoliths were subjected to acid digestion to analyse the trace elements (Ca, Na, Mg, Sr, Mn, Ba, Fe and K) using ICP ‐ AES . Data were subjected to appropriate statistical treatments, such as univariate anova , ancova , manova and DFA in order to delineate the fish stock(s) accurately. Mean concentrations of Ca, Mg, Sr, Mn, Ba, Fe and K in the otoliths of the fish from selected sites of the different rivers were significantly (P < 0.001) different from each other, while the mean Na concentrations were comparable (P > 0.05). In classification statistics, 96% of individuals were correctly classified to their original groups. The scatter plot of DF ‐I vs DF ‐ II depicted the presence of different stocks in the R iver G anga and its selected tributaries. Variations in the microchemistry of the otoliths showed the presence of four C . punctata stocks in the three selected rivers.