Age-specific accumulation of toxic metal(loid)s in northern pike (Esox lucius) juveniles

Northern pike specimens of 0+, 1+, and 2+ age classes were collected in June 2013 from the Vizelj channel near Belgrade (Serbia). Inductively coupled plasma optical spectrometry (ICP-OES) and atomic absorption spectrometer SpectrAA 220 were used for analyzing concentrations of As, Cr, Cd, Co, Cu, Fe, Sr, Pb, and Zn, as well as Hg in muscle, gills, and liver. Metal pollution index (MPI) was calculated. Concentrations of As, Cd, Co, and Pb were below the limit of detection. Concentrations of Cu, Hg, and Zn in muscle did not exceed the maximum allowed concentrations. The gills were tissue which was most affected by pollution. The highest concentrations of Fe in muscle, Cr and Fe in gills, and Hg, Sr, and Zn in liver were recorded in 0+ individuals, as well as Zn in gills of 2+ individuals. On contrary, the lowest concentrations were recorded for Zn in gills of 0+ individuals, Hg in gills of 1+ individuals, and Fe in muscle, Cr and Sr in gills, and Zn in liver of 2+ individuals. Regarding age classes, 2+ juveniles had the highest MPI values for all tissues. Correlations between the metal(loid) accumulation and fish condition were not significant, as well as between fish length and weight and Cu and Hg in muscle, Cu, Hg, and Sr in gills, and Cu, Cr, and Fe in liver. Results indicated that young individuals were more sensitive to pollution, but older fish showed higher overall bioaccumulation of toxic elements analyzed in this study.