Strontium and zinc concentrations in otoliths of common fish species in the northern Baltic Sea

Otoliths of perch (Perca fluviatilis), pike (Esox lucius) and European whitefish (Coregonus lavaretus) caught at different locations in the northern Baltic Sea along the Finnish west coast and at some rivers and lakes were subjected to elemental analyses with particle induced X-ray emission and laser ablation inductively coupled plasma mass spectrometry. The strontium concentration in otoliths from whitefish (similar to 3300 µg/g) was 2-3 times higher than that of perch and pike (similar to 1400 µg/g), while within species the strontium concentration of otoliths from fish caught at different locations was in the same range. The strontium concentrations were lowest in fish from the lakes (similar to 450 µg/g). Whitefish otoliths contained more zinc (similar to 60 µg/g) than those of pike (similar to 30 µg/g), while the zinc concentration in perch otoliths were below the detection limit. No spatial intraspecies variations in zinc concentrations were observed. X-ray diffraction showed that the otoliths consisted of aragonite solely.