黄海南部近岸带鱼鱼卵分布及仔鱼输运模式

Study on the distribution of eggs and larval transport of largehead hairtail,Trichiurus japonicus in the coastal southern Yellow Sea

基于2018—2022年对黄海南部近岸海域(119°E~124°E,33°N~37°N)的鱼类浮游生物综合调查获得的带鱼鱼卵的丰度数据确定粒子释放区,利用有限体积海岸模型(Finite-volume coastal ocean model,FVCOM),结合拉格朗日粒子追踪算法,模拟了带鱼仔鱼阶段的个体输运过程,以了解黄海南部带鱼的繁殖期、产卵场和育幼场分布,及海洋环境对卵、仔鱼分布和扩散的影响。结果表明,研究海域带鱼春夏季产卵,5、7、8月均有带鱼鱼卵出现,8月为繁殖盛期;带鱼鱼卵5月主要分布在近岸19~30 m水域,而8月则广布于11~70 m水域;带鱼鱼卵出现海域的海表温度(Sea surface temperature,SST)、海底温度(Sea bottom temperature,SBT)分别为13.9~29.7、8.4~28.3℃。随机森林(Random forest)算法分析结果表明,温度和水深是影响带鱼鱼卵丰度的主要环境因子。粒子追踪模拟实验结果显示,5月释放的粒子,在1~15 d(鳔未形成、仔鱼无垂直迁移行为)个体主要表现为向粒子释放区西北近岸一带扩散,在16~40 d个体出现昼夜垂直迁移行为后,粒子离开近岸向东扩散至50 m水深附近。7月和8月,在发生垂直迁移行为前,个体在近底层主要从释放区向近岸扩散,发生昼夜垂直迁移行为后,个体从近岸聚集区稍向离岸方向移动;部分释放于外侧水域的粒子则产生向北和东北方向的短距离扩散,扩散模式在整个仔鱼阶段未有显著改变。8月调查获得的带鱼仔鱼聚集区特征与粒子输运模拟实验结果较为一致。我们认为产卵的季节、空间位置,仔鱼垂直迁移特性及区域上升流和锋区结构等是影响带鱼仔鱼输运模式的主要因素。研究结果可为理解黄海南部带鱼鱼卵、仔鱼阶段的栖息地选择机制与早期补充动态及带鱼资源的管理和保护提供科学依据。

This study determined the particle release area based on the abundance data of largehead hairtail eggs obtained from the ichthyoplankton surveys in the coastal waters of the southern Yellow Sea(119°E-124°E,33°N-37°N)conducted from 2018 to 2022.Subsequently,the Finite-volume Coastal Ocean Model(FVCOM)coupled with the Lagrangian particle tracking algorithm was employed to simulate the transport process of largehead hairtail larvae.The primary objectives were to investigate the spawning periods,spawning grounds,and nursery habitats of largehead hairtail in the southern Yellow Sea,and to assess the influence of oceanic conditions on the egg distribution and larval dispersion.The results indicated that largehead hairtail spawned in spring and summer in the southern Yellow Sea with the eggs appeared in May,July and August,and August was the peak spawning month.Largehead hairtail eggs were mainly distributed in 19-30 m waters in May,and 11-70 m waters in August.The sea surface temperature and sea bottom temperature for the presence of largehead hairtail eggs was 13.9-29.7 and 8.4-28.3℃ respectively.The Random Forest model analysis revealed that water temperature and depth were the main environmental factors affecting the abundance of largehead hairtail eggs.Particle tracking simulation experiments showed that the particles released in May mainly spread towards the northwest coastal area of the particle release area after 1-15 days(when the swim bladder has not formed and the larvae have no vertical migration behavior),and after 16-40 days(when the swim bladder has formed and the larvae have vertical migration behavior),the particles left the coastal area and spread eastward to the waters near a 50 m water depth.In July and August,before the occurrence of vertical migration behavior,larvae stayed in the near-bottom layer and most of them were transported from the release area to the nearshore waters;After that,larvae moved slightly from the nearshore aggregation area to the off-shore direction.Some of the individuals released in the offshore deep-water areas spread to the north and northeast in a short-distance,and the dispersal pattern did not change significantly in their whole larval stages.Aggregation areas of largehead hairtail larvae derived from field surveys in August were consistent with the results of particle transport simulation experiments.We thought that the season and spatial location of spawning,the diel vertical migration characteristics of larval fish,and the regional upwelling and frontal structure were the dominant factors that shape the transport pattern of largehead hairtail larvae.The results of the study provide a scientific basis for understanding the habitat selection mechanism of egg and larvae stages and early replenishment dynamics of this fish in the southern Yellow Sea,and help for the management and protection of largehead hairtail resources.