Application of enriched 137Ba tracer to mark juvenile Persian sturgeon (Acipenser persicus)

Abstract

The present study evaluates the variations of 137Ba abundance in pectoral fin spine of 1-month-old juvenile Persian sturgeon (Acipenser persicus) upon marking using the stable isotope approach. The marking of the fish was achieved by incorporation of 137Ba2+ in the calcified lattice of the pectoral fin spine through substitution with structural Ca2+. This process was carried out by rearing juveniles in treatment tanks containing elevated concentrations of 137Ba for 1, 3 and 5 days. The marked fish were then retained in natural abundance fresh and brackish waters, to evaluate the trend of exchange of 137Ba from the fin spines. The abundance of 137Ba in fin spines during marking and post-marking experiments were detected by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that a significant isotope mark can be obtained with no mortality and 100% marking rate on the first day of exposure to the isotope. The marked juveniles maintained their isotopic signature for at least 25 days. Statistical analysis of the obtained 138Ba/137Ba ratios demonstrated that the successful incorporation of 137Ba2+ in pectoral fin spines provides an effective marking method for Persian sturgeon restocking programs.