多鳞四指马鲅5个地理群体的形态差异

为探讨不同地理群体多鳞四指马鲅形态差异，实验基于2018—2019年采自海门、如东、舟山、三门、珠海5个地理群体的133尾多鳞四指马鲅个体进行35个可量性状和8个可数性状测定，并拍摄保存样本照片用于几何形态学分析。多鳞四指马鲅的传统形态学和几何形态学分析结果显示，5个地理群体的多鳞四指马鲅形态特征存在一定程度的差异，且和地理距离成正相关，但尚未达到种群分化的程度。这可能是更新世冰期时，海平面下降导致南海和东黄海之间形成地理隔离所致；但随更新世末期海平面上升，因多鳞四指马鲅极强的洄游习性，仍有部分群体可以在黄海和南海之间进行长距离洄游，以及鱼卵和仔稚鱼存在随洋流扩散从而群体间存在不同程度的基因交流，导致不同地理群体间虽存在着较大的形态特征差异，但形态和遗传分化仍未能达到种群分化水平。综上，鉴于不同地理群体的多鳞四指马鲅在不同海域繁殖、索饵出现的时段差异，建议对这5个地理群体中的三门群体和舟山群体划为2个管理单元，如东群体和海门群体划为1个管理单元，珠海群体划为另1个独立的管理单元。针对5个地理群体按4个管理单元进一步制定特别管理政策，以期既保护渔业资源可持续发展又保障广大渔民的生计。

Morphological differences of five Eleutheronema rhadinum geographical stocks

In order to explore the morphological differences of the Eleutheronema rhadinum in different geographical groups, this article was Based on 133 E. rhadinum individuals collected from Haimen, Rudong, Zhoushan, Sanmen and Zhuhai from 2018 to 2019, 35 measurable traits and 8 countable traits were measured, and photos of preserved samples were taken for geometric morphological analysis. In the traditional morphological analysis, ANOVA results showed that there were significant differences in other factors except the anal length/body length. Principal component analysis results showed that the variance contribution rates of the first three principal components were 27.724%, 23.959%, 13.535%, and 65.218%. Cluster analysis results showed that there was no significant morphological difference among geographic groups. In the geometric morphology analysis, the results of overprint analysis showed that the marks 5, 4, 7, 7 and 9 had A great influence on the external morphology of E. rhadinum. The results of principal component analysis showed that the first three principal components contributed 21.25%, 18.41%, 12.60% , and the cumulative contribution was 52.25%. The results of principal component cluster analysis showed that there was no morphological difference. In the typical variable analysis results, CV1 contributed 71.059%, CV2 contributed 18.192%, and CV1 and CV2 plotted the two-dimensional scatter diagram of typical variables with staggered distribution of each group sample. The results of Mahalanobis distance and Przewalski distance of different geographical groups showed that there were no significant morphological differences among different geographical groups.The results of both traditional morphology and geometric morphology analysis showed that the morphological characteristics of E. rhadinum in among 5 geographical groups were different to a certain extent, and were positively correlated with geographical distance, but had not yet reached the level of population differentiation. This may be due to the geographical isolation between the South China Sea and the East Yellow Sea caused by the fall of sea level during the Pleistocene Glacial Age. However, with the rise of sea level at the end of Pleistocene, because of the strong migration habit of E. rhadinum, some groups could still migrate long distance between the Yellow Sea and the South China Sea, and the presence of fish eggs and larvae that spread with ocean currents, resulting in different levels of gene exchange between populations. As a result, although there are differences in morphological characteristics among different geographical groups, the morphological and genetic differentiation still cannot reach the level of population differentiation.In view of the time difference of E. rhadinum reproductive migration of different geographical groups in the corresponding sea area, it was suggested that these 5 geographical groups be divided into 1 management unit of Sanmen group, 1 management unit of Zhoushan group, 1 management unit of Rudong group and Haimen group, and another independent management unit of Zhuhai group. In order to protect the sustainable development of fishery resources and guarantee the livelihood of fishermen, targeted management policies should be further formulated and implemented according to four management units for five geographical groups.