Study of the Feasibility of Identifying the Group of Released Liza haematocheila by Using the Strontium Marking Method in Otoliths

Abstract:

To study the feasibility of using the strontium marking method in otoliths to identify the group of released Liza haematocheila, juveniles with a total length of ~5 cm were immersed in four different concentrations (50, 100, 200, and 400 mg/L) of Sr2+ for 48 h to detect the Sr2+ sedimentation effect. A double ring marking experiment was also conducted: L. haematocheila juveniles with a total length of about 3 cm were immersed in seawater with Sr2+concentrations of 200 mg/L, for 96 h. When the length of the first marked juveniles reached 5 cm, half of them were again immersed in seawater with Sr2+ concentrations of 100 mg/L, for 48 h. A significant peak was observed in EPMA (electron probe microanalysis) line transect analysis and a "high strontium marking ring" appeared in EPMA mapping analysis of L. haematocheila otoliths in all the marked treatments. Based on the results of the experiment and the marking efficiency, we suggest that a marking concentration of 50 mg/L Sr2+ could be used for strontium marking on otoliths of L. haematocheila. A well-structured double marking ring was observed in EPMA mapping analysis of L. haematocheila otoliths in double ring marking treatment, and the EPMA line transect analysis result of each ring in double-ring marking juveniles otoliths was the same as that in the corresponding monocyclic ring treatment. These results suggest that it is feasible to identify different groups of released L. haematocheila by changing the strontium marking times.