中文摘要：

为确认鄱阳湖中是否仍存在有溯河洄游的刀鲚个体，利用x射线电子探针微区分析技术（EPMA）研究了采自鄱阳湖星子县水域2尾刀鲚个体矢耳石的锶和钙微化学特征。定量线分析结果显示，上颌骨较短个体（PYCB02）的耳石锶钙比值（即Sr／Ca×1000）为稳定的低值（1．66±0．54），反映了其淡水定居的生活习性；而上颌骨较长个体（PYCE05）的锶钙比值波动显著，不仅具有对应淡水生活的低值（1．82±0．50），而且出现了对应于海水生活的高值（5．79±0．91），显示出其溯河洄游的“履历”。这些结果更得到了耳石元素面分布分析结果的支持。这两种截然不同的耳石微化学特征类型首次直观地反映和证实了目前距长江河口约800km的鄱阳湖中同时存在有溯河洄游和淡水定居的两类刀鲚个体。

英文摘要：

To confirm whether there is anadromous estuarine tapertail anchovy Coilia nasus now in Poyang Lake, an electron probe microanalyzer（EPMA） was applied to analyze the element Sr and Ca microchemistry patterns in otoliths of two individuals collected from Xingzi area of the lake. Results of line transect analysis showed that the ratios of Sr： Ca x 1 000 in the otolith of the individual with a shorter supramaxilla（PYCB02） were consistently low （ 1.66 ± 0.54）, indicating that it experienced in freshwater habitat during its whole life history. Another individual with a longer supramaxilla （ PYCE05 ） had a complex Sr/Ca ratio pattern which can be divided into three phases （1.82 ± 0.50,5.79 ± 0.91, and 4.14 ± 0.88 ）, suggesting it experienced not only the freshwater, but also the seawater and brackish water during different stages in its life history. All these differences could be well confirmed by the results of X-ray mapping analysis of EPMA. The whole otolith of PYCB02 presented a uniform bluish pattern（low Sr level）from the core to the outermost regions. In contrast,the otolith of PYCE05 showed a multi-color pattern. There were greenish （moderate Sr level）, yellowish（ moderate Sr level）, or even reddish （high Sr level）in outer regions adjacent to the bluish central regions. Results of the two different microchemistry patterns obtained by both the line transect and mapping analyses confirmed objectively, for the first time,the coexistence of resident and anadromous forms of Coilia nasus in Poyang Lake and suggested that Coilia nasus is still possible to migrate anadromously for spawning into Poyang Lake, which is about 800 km away from the river mouth of Yangtze River. These aforementioned microchemistry patterns will provide important information not only to more effectively evaluate and protect the resources of Coilia nasus, but also to rationally plan and guide future ecological economic development in Poyang Lake.