基于GAM的黄海南部越冬小黄鱼资源丰度与环境因子关系

Relationship between environmental factors and abundance of overwintering Larimichthys polyactis in the southern Yellow Sea based on GAM

为探究小黄鱼(Larimichthys polyactis)资源丰度随环境变化的响应规律并将其应用于小黄鱼资源预测和管理,根据2010—2019年冬季(12月—2月)黄海南部小黄鱼渔获数据,基于核密度估计法分析越冬期间小黄鱼资源分布情况,并结合相应海域底层温度、底层盐度、叶绿素a浓度以及水深数据,运用广义可加模型(GAM)研究黄海南部越冬小黄鱼资源丰度与环境因子的关系。结果显示,黄海南部越冬期间小黄鱼资源呈现明显的聚集性特征,主要分布在32°24′~34°00′N、123°00′~125°00′E区域,而各月份小黄鱼资源分布情况有所不同。GAM模型累积偏差解释率为54.4%,其中贡献最大的环境因子为水深(34.3%),最小为叶绿素a浓度(4.6%)。2010—2017年黄海南部越冬小黄鱼资源丰度的年际变动较小,2017年后资源丰度有所上升。随着水深的增加,小黄鱼资源丰度呈现先下降后上升趋势。底层温度对小黄鱼越冬资源丰度影响波动较大,但整体上资源丰度随着温度升高而振荡上升。底层盐度范围在32.8~33.5时,小黄鱼资源丰度随着盐度的升高而明显上升;当盐度大于33.5时,小黄鱼资源丰度基本保持稳定。越冬小黄鱼资源丰度与叶绿素a浓度并非是完全正相关关系。

Owing to global climate change and unprecedented fishing activities,the spatiotemporal distribution of small yellow croaker Larimichthys polyactis has changed dramatically.Therefore,it is urgent to analyze the relationships between resource abundance of Larimichthys polyactis and environmental factors of its inhabiting waters,such as sea bottom temperature(SBT),sea bottom salinity(SBS).In this study,kernel density method was used to analyze the distribution of Larimichthys polyactis based on the catch data in the southern Yellow Sea from December,January,and February of each year from 2010 to 2019.Generalized additive model(GAM)was applied to explore the relationships between environmental factors(SBS,SBT,chlorophyll-a concentration,and water depth data)and spatiotemporal distribution of overwintering Larimichthys polyactis in the southern Yellow Sea.The results showed that Larimichthys polyactis mainly distributed in 32°20′-34°00′N and 123°00′-125°00′E,but with obvious aggregation in different months.The high value of kernel density of Larimichthys polyactis resources in December was mainly concentrated in the sea area of 32°48′-33°48′N,123°00′-124°10′E.With the gradual decrease of water temperature,Larimichthys polyactis in the southern Yellow Sea in January and February continued to migrate offshore,i.e.,concentrated in the area of 32°20′-34°00′N,123°24′-125°00′E.It showed a southeast-northwest distribution,which was consistent with the main axis position and flow direction of the Yellow Sea warm current in the southern Yellow Sea in winter.The accumulation of deviance explanation of GAM model was 54.4%.The environmental factor with the largest deviation explanation was water depth(34.3%)while the smallest was chlorophyll-a concentration(4.6%).There was no significant change in the abundance of overwintering Larimichthys polyactis in the southern Yellow Sea from 2010 to 2017,and the abundance increased slightly after 2017.With the increase of water depth,the catch per unit effort(CPUE)Larimichthys polyactis first decreased and then increased.The effect of sea bottom temperature on the CPUEof fluctuated greatly,but it overall increased with the increase of temperature.When the sea bottom salinity ranged from 32.8 to 33.5,the CPUE of Larimichthys polyactis increased significantly with the increase of salinity;when the salinity was greater than 33.5,it remained relatively stable.The correlation between resource abundance of Larimichthys polyactis and chlorophyll-a concentration was not completely positive.This study provided a scientific basis for overwintering ground prediction of Larimichthys polyactis and its resource management.