Comparison of otolith microchemistry of reproductive and non-reproductive female kutum (Rutilus frisii kutum)

To study the spawning migration of five-year-old reproductive and non-reproductive female kutum, Rutilus frisii kutum, the trace elements of Sr, Ba, Ca and the ratios of Sr:Ca, Ba:Ca and Sr:Ba were examined in their otoliths using ICP-MS. Water and fish samples were collected from the southern part of the Caspian Sea in reproductive season (February and March) of kutum. The concentration of Sr in Caspian Sea was twice than river while there was insignificant difference between two habitats in terms of Ba levels. Statistical comparison between reproductive and non-reproductive female kutum revealed small difference in the concentration of otolith Sr, but showed significant difference in Ba:Ca ratio. Differences in Ba:Ca ratio could be the result of fish migration towards the coastal zones over reproductive season and feeding of non-reproductive individuals in estuarine areas. Results indicated that microchemical analyses of otolith can be used as a valuable tool for differentiate reproductive and non-reproductive individuals. By means of elemental content relative to calcium, two types of fish could be differentiated for better understanding the movement pattern of fish broodstock, which could be completed with data from the other methods like tagging.