Research on Threshold Value of Sr2+and Efficiency of Different Sr2+Concentrations during the Period of Strontium Marking in Liza haematocheila
In order to determine the lowest Sr2+added during the strontium of L.haematocheila were marked for 48 h,the juveniles were taken as the experimental material.The marking effects of different external Sr2+concentrations(2.5,5,10,15,20,40 and 80 mg·L-1)during the strontium Strontium marking of L.haematocheila were studied.The results showed that the"high strontium mark-ing ring"was detected in otoliths of fish in all treatments added more than 20 mg·L-1 Sr2+,and no significant difference was observed in survival rate among all treatments.Although the peak value of the Sr/Ca and the width of the marking ring of the otolith were in-creased with the more exogenous Sr2+being used,the standardized marking efficiency was significantly decreased.In conclusions,the method of strontium marking on otoliths of L.haematocheila is feasible and safe,the mode of the seawater Sr2+concentration being in-creased by 20 mg·L-1 and L.haematocheila being marked for 48 h is suggested as an optimized marking mode,which will reduce cost of large number juveniles being marked.