南海北部近海新记录种——苏门答腊金线鱼资源分布特征

Stock distribution of a new record species Nemipterus mesoprion in offshore northern South China Sea

  • 摘要: 苏门答腊金线鱼 (Nemipterus mesoprion) 是近年来中国海域确定的金线鱼属新记录种,对其资源状况认知较缺乏。根据2014—2015年南海北部近海4个季节的底拖网渔业资源调查数据,分析苏门答腊金线鱼群体的体长-体质量关系,并应用空间统计方法探索该鱼种的资源分布与格局特征。结果表明苏门答腊金线鱼样本的体长-体质量呈显著的幂函数关系 (R2>0.96),无性别差异。估算的参数b约为3,种群趋向于等速生长模式。从时间上看,资源分布存在季节变化,资源密度和丰度均以夏季最高而春季最低。该鱼种资源量总体较低,四季资源密度和丰度均值分别为0.41~2.29 kg·km−2和44.38~147.69 尾·km−2。从空间分布看,苏门答腊金线鱼主要分布于北部湾,该湾20°N以北是资源高值区。标准差椭圆分析结果表明苏门答腊金线鱼的4个季节资源主分布方向呈逆时针变化,从准正北-正南向西北-东南再转向至东北-西南,种群分布格局为先聚集后分散。资源密度和丰度的重心季节变化均是先向北移动再转向东南方向迁移。

     

    Abstract: Nemipterus mesoprion has been identified as a new recorded species Nemipterus in Chinese waters in recent years, but there is little understanding of its resource status. Thus, based on the fishery resources data from the bottom-trawl survey in the offshore northern South China Sea during four seasons of 2014−2015, we analyzed the relationship between the body length and body mass for N. mesoprion population, and explored its stock distribution and spatial pattern by using spatial statistics method. The body length-mass relationship for N. mesoprion samples exhibited a significant power function with R2 greater than 0.96, which had no difference between sexes. Besides, the population tended to follow an isometric growth pattern as the estimated parameter b was about three. In terms of temporal scale, the stock distribution showed a seasonal variation with the greatest biomass in summer and the smallest in spring for both the stock density and abundance. Generally speaking, its stocks were small, and the average stock density and abundance in four seasons were 0.41−2.29 kg·km−2 and 44.38−147.69 ind·km−2, respectively. In the aspect of spatial distribution, N. mesoprion was mostly distributed in Beibu Gulf, especially for the high-stock zone in northern area of 20°N. The result for standard deviational ellipse indicates that the main distribution direction of N. mesoprion in four seasons was counterclockwise (from quasi-north-south to northwest-southeast then to northeast-southwest), and the population distribution pattern followed a trend of aggregation to dispersion. The seasonal change in gravity center for both stock density and abundance was towards northward and then southeast.

     

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