黄海中部近岸产卵场小黄鱼卵子的自然死亡特征

Natural Egg Mortality of Small Yellow Croaker ( Larimichthys polyactis) ,Inhabiting the Coastal Spawning Ground of Central Yellow Sea

鱼类早期生活史阶段的死亡是影响群体补充量动态及种群结构的重要因素。为探究中国近海重要经济鱼种小黄鱼(Larimichthys polyactis)早期补充阶段的自然死亡特征,本文根据2013—2018年春季黄海中部(34.4°N—35.6°N、119°E—122°E)水深20 m以内海域的浮游生物调查数据,基于马尔科夫链构建了鱼卵自然死亡评估模型,分析了小黄鱼卵子的自然死亡特征,初步研究了海水表层温度、海水表层盐度、水深、卵子密度、离岸距离等环境因子对小黄鱼卵子死亡的影响。研究表明,在小黄鱼卵子的不同发育阶段卵子的死亡量值变化显著,Ⅱ期阶段死亡概率、瞬时死亡率最高。以死亡概率计,小黄鱼Ⅱ期卵子死亡概率的变化范围是0.80~0.98,平均为0.87;Ⅲ期卵子死亡概率的变化范围是0.05~0.81,平均为0.46;Ⅳ期卵子死亡概率变化范围是0.62~0.78,平均为0.68;以瞬时死亡率计,小黄鱼Ⅱ期卵子瞬时死亡率变化范围是16.43~364.24 d^(-1),平均为93.50 d^(-1);Ⅲ期卵子瞬时死亡率变化范围是0.09~16.94 d^(-1),平均为5.66 d^(-1);Ⅳ期卵子瞬时死亡率变化范围是3.18~7.31 d^(-1),平均为4.83 d^(-1)。调查未采集到小黄鱼Ⅴ期卵子。小黄鱼卵子的自然死亡呈显著的年度差异,2017—2018年小黄鱼Ⅱ期卵子的瞬时死亡率较2013—2015年显著上升。与东北大西洋的大西洋鲭(Scomber scombrus)和竹荚鱼(Trachurus trachurus)的Ⅱ、Ⅲ、Ⅳ、Ⅴ期卵子的瞬时死亡率相比,黄海小黄鱼卵子的瞬时死亡率显著偏高。本研究初步揭示了黄海小黄鱼卵子的自然死亡特性,研究结果可为小黄鱼早期补充动态和资源保护提供参考。

The mortality of fish at the early life stages is an important factor affecting the population dynamics and structure of fish populations.In order to document the early life stage natural mortality characteristics of important economic fish species,Larimichthys polyactis,inhabiting Chinese coastal waters,in this study,we analyzed the ichthyoplankton survey data collected from the shallow waters(depth≤20 m)of the central Yellow Sea(34.4°N—35.6°N,119°E—122°E)in the spring of 2013 through 2018.A Markov chain was used to construct a model for assessing the natural mortality characteristics of eggs of L.polyactis eggs documented.In this study,we also determined the effects of environmental factors including sea surface temperature and salinity,water depth,fish egg abundance,and offshore distance among others on the mortality of L.polyactis eggs.The results showed that the mortality of L.polyactis eggs varied significantly among developmental stages with the highest mortality probability and instantaneous mortality rate occurred at stageⅡ.The mortality probability of stageⅡeggs ranged from 0.80 to 0.98 with an average of 0.87.The mortality probability of stageⅢeggs ranged from 0.05 to 0.81 with an average of 0.46.The mortality probability of stageⅣeggs ranged from 0.62 to 0.78 with an average of 0.68.The instantaneous mortality rate of stageⅡeggs ranged from 16.43 to 364.24 d^(-1) with an average of 93.50 d^(-1).The instantaneous mortality rate of stageⅢeggs ranged from 0.09 to 16.94 d^(-1) with an average of 5.66 d^(-1).The instantaneous mortality rate of stageⅣeggs ranged from 3.18 to 7.31 d^(-1) with an average of 4.83 d^(-1).StageⅤeggs of L.polyactis were not collected in the survey.The natural mortality of L.polyactis eggs showed a significant annual difference with the instantaneous mortality rate of stageⅡeggs increased significantly from the first three years(2013—2015)to the last two(2017—2018).Compared to the instantaneous mortality rate of stagesⅡ—Ⅴeggs of Atlantic mackerel(Scomber scombrus)and Atlantic horse mackerel(Trachurus trachurus)in Northeast Atlantic,the instantaneous mortality rate of L.polyactis eggs in Yellow Sea was significantly higher.Our findings provided important reference information for the dynamics and conservation of L.polyactis populations.