耳石锶标记识别鮻放流群体的可行性研究

为探究耳石锶(Sr;)标记技术在鮻(Liza haematocheila)增殖放流群体识别的可行性,以体长5 cm左右的鮻幼鱼为研究对象,将其养殖海水中Sr;的质量浓度分别调至50、100、200和400 mg/L,以自然海水(Sr;质量浓度为7.9 mg/L)为对照组,人为改变鮻幼鱼生存环境中Sr;的质量浓度标记48 h。同时开展双环标记实验(在鮻3 cm幼鱼时进行Sr;质量浓度200 mg/L海水96 h标记,待其长至5 cm幼鱼时进行Sr;质量浓度100 mg/L海水48 h标记)。实验结果显示,Sr;质量浓度50;00 mg/L的海水48 h标记的鮻耳石Sr/Ca比均出现一个显著的上升阶段且面分析出现明显的"高Sr;标记环"。综合本研究结果和标记效率,推荐采用Sr;质量浓度为50 mg/L的海水进行鮻耳石Sr;标记。双环标记实验鮻耳石Sr;元素面分布结果出现层次分明的双环,且双环标记组鮻耳石2条不同标记环的线性分析结果与其相对应的单环标记组基本一致,这表明通过Sr;标记次数来进行不同放流群体识别是可行的。

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

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.