Stable isotopic composition of otoliths in identification of stock structure of small yellow croaker(Larimichthys polyactis) in China

Oxygen and carbon isotope ratios（δ^（18）O and δ^（13）C） in otoliths were used to identify the stock structure of small yellow croaker,Larimichthys polyactis.Otoliths were collected from fish at five locations across the Yellow Sea and the Bohai Sea representing most of their distributional range and fisheries areas.The significant differences in the isotopic signatures showed that the five locations could be chemically distinguished and clearly separated,indicating stock subdivision.Correlation of δ^（18）O and δ^（13）C values suggested that population of L.polyactis could be divided into the Bohai Sea group,the southern Yellow Sea group and the central Yellow Sea group.Discriminant analysis of δ^（18）O and δ^（13）C values demonstrated a high significant difference with 85.7% classification accuracy.The spatial separation of L.polyactis indicated a complex stock structure across the Yellow Sea and the Bohai Sea.These results indicate that optimal fisheries management may require a comprehensive consideration on the current spatial arrangements.This study has provided further evidence that measurement of the stable isotopes ratios in otolith can be a valuable tool in the delineation of fishery management units.

Analyses of egg size,otolith shape,and growth revealed two components of small yellow croaker in Haizhou Bay spawning stock

The geographical variations in life history characteristics of small yellow croaker Larimichthys polyactis, caused by experienced different environmental conditions, have been observed in China seas. Previous studies based on spatial distribution, migration route, and body morphometrics suggested a complex stock structure. In this study, to clarify the source of a spawning stock, we investigated the reproduction strategy and inter-structure of the Haizhou Bay (HZB) spawning stock in the middle Yellow Sea from both egg survey and adult otolith increment analysis. Egg and adult samples were collected from three surveys during spawning season in 2013. Distinct spatial and temporal variations were detected in egg distribution and size, and otolith shape analysis of adult fishes revealed two morphotypes with different increment growth using random forest cluster. The results indicate the existence of two components within the same spawning stock in HZB from different wintering grounds, and accordingly special protection should be required for this stock given the significance to maintain connectivity between adjacent subpopulations.

基于耳石微化学的东海大黄鱼洄游路线推测

近年来,东海频现对大黄鱼(Larimichthys crocea)大网捕获(吨级规模以上),引起了对衰退中的野生大黄鱼资源保护的担忧。为查明东海野生大黄鱼洄游规律,本文根据2020-2022年在浙江近海产卵场和外海越冬场采集的不同批次野生大黄鱼样本,利用激光剥蚀电感耦合等离子体质谱法(LA-ICP-MS)测定耳石微化学元素,结合聚类分析和主成分分析(PCA),对不同大黄鱼群体进行了划分,结合耳石的年轮特征,研究大黄鱼群体的栖息生境,推测大黄鱼洄游路线。结果表明,Ba/Ca≤0.004 2时可以判定为海洋栖息生境,Ba/Ca≥0.008 1时可以判定为河口栖息生境,0.004 2 <Ba/Ca<0.008 1时可以判定为混合栖息生境。根据该阈值范围,判定本次采样的大黄鱼的5种生境类型:(1)近海产卵,近海混合水域短暂栖息类型(占22.2%);(2)近海产卵,阶段性往复混合生境栖息类型(占15.6%);(3)近海产卵,河口水域育幼索饵,外海越冬栖息类型(31.1%);(4)河口产卵、混合水域育幼,外海越冬栖息类型(6.7%);(5)近海混合水域短暂产卵,绝大部分时间海洋生境栖息类型(24.4%)。对所有样本的Ba/Ca核心、峰值和边缘值进行PCA,5种栖息类型的样本均匀分布在第一轴的两侧,大部分时间都在海洋生境中的G1、G2和G5,以及受陆源影响较大的G3和G4。同时,PCA结果同时也显示,5种类型样本均会近同步地在近海岛礁处出现,这表明外海、近海和河口的群体由于洄游等因素的影响会出现混合,说明了舟山岛礁水域对大黄鱼产卵育幼的重要性。本研究为东海大黄鱼近海产卵场、索饵场和外海越冬场之间洄游履历,以及大黄鱼洄游路线推测提供一定依据。

黄、渤海小黄鱼耳石元素指纹分析及其在种群补充群体识别中的应用

利用电感耦合等离子质谱ICP-MS元素分析方法,测定了黄、渤海125尾小黄鱼的耳石元素指纹图谱,共检测到Mg、Al、Mn、Cu、Zn、Sr、Ba、Ca等8种指纹元素。不同采样站位小黄鱼耳石元素含量均存在显著性差异,线性判别分析可以有效识别不同站位的小黄鱼群体,判别成功率为65%～96%,整体判别成功率为86%。基于耳石元素指纹图谱特征进行聚类分析,可以将黄、渤海小黄鱼早期补充群体划分为渤海种群、黄海中部种群和南黄海种群,其中黄海中部种群站位交叉明显。

耳石形态在长江口小黄鱼生活史研究及群体识别中的应用

本研究以长江口春(5月)、秋(11月)两季的小黄鱼(Larimichthys polyactis))耳石为研究对象,将10个耳石度量指标与鱼体体长、体质量进行函数关系拟合,并分析耳石绝对尺寸和相对尺寸与鱼体体长的关系;同时利用主成分分析法(PCA)得到耳石圆度(I2)和Feret比(I9)可以代表10个耳石形态指标,用于解析小黄鱼耳石形态特征,并结合耳石绝对尺寸和耳石相对尺寸探讨耳石形态与小黄鱼特殊生活阶段的关系。另一方面,利用形态指标法(Shape index)及傅里叶分析法(Fourier analysis)探讨了小黄鱼耳石形态在不同季节生态群体中的识别应用。结果表明,幂函数拟合耳石度量指标与鱼体体长、体质量效果最佳,耳石长轴(耳石最大半径、耳石长、耳石最大Feret径长)与体长、体质量的关系拟合效果较短轴(耳石最小半径、耳石宽、耳石最小Feret径长)更佳,且在耳石相对尺寸中,长轴的变化趋势相对稳定,因此在近海小黄鱼的渔业资源评估中,利用耳长轴来推算鱼体体长及体质量更为合理;同时发现,在体长为110和160mm时,耳石圆度(I2)分别出现减小速率变缓的拐点,Feret比(I9)分别出现增大速率变缓的拐点,且耳石绝对厚度和耳石相对厚度也在体长110~170mm时出现大幅变化,这与小黄鱼的性成熟体长(108mm)及生长速率变缓的拐点体长(169.2mm)接近,推测耳石形态可有效地记录了小黄鱼性成熟时期及各生长阶段的变化。在群体识别方面,单用耳石形态指标得到的判别成功率为85.4%和81.7%,信息有效占比60.0%,单用傅里叶分析值得到的判别成功率为84.8%和85.2%,信息有效占比36.4%,结合两种指标得到的判别成功率为92.7%和91.3%,表明利用多种耳石形态指标可提高群体识别成功率,而耳石形态指数可更有效地提取耳石信息;耳石形态在春秋两季生态群体中有较高的识别率,个体耳石形态差异较大,本研究认为这与长江口不同季节的环境变化有关。

8种含碳酸盐的矿物类中药的近红外光谱特征谱段分析

目的：探讨含碳酸盐的矿物类中药的物相组成,主要成分含量与其近红外光谱特征的相关性,确定含碳酸盐的矿物类中药的近红外光谱特征谱段。方法：采用X衍射法、EDTA滴定法、近红外光谱法对南寒水石、钟乳石、石燕、石蟹、石花、炉甘石、鱼脑石、鹅管石8种含碳酸盐的矿物类中药的物相组成、主成分含量、近红外光谱特征进行分析,探究矿物类中药近红外特征谱段的选择。结果：8种含碳酸盐的矿物类中药的近红外特征谱段中确定6 070~5 000 cm-1和4 800~4 050 cm-1为建模特征谱段,剔除7 350~6 500 cm-1具有合理性。结论：结合X衍射分析结果对近红外光谱特征进行对比分析,可以有效地识别含碳酸盐类矿物类中药的特征谱段,有利于建立合理有效的近红外分析模型。