南澳岛海域渔业资源声学评估与空间分布

Acoustic assessment of fishery resources and spatial distribution in Nan'ao Island area

基于2014年秋季和2015年春季南澳岛海域渔业资源声学与底拖网调查数据,对该海域主要渔获物种类、资源动态与空间分布进行了评估分析。结果表明优势种类存在较大差异,短尾大眼鲷(Priacanthus macracanthus)和鹿斑鲾(Secutor ruconius)分别为秋季和春季主要优势鱼类。秋季和春季声学评估种类平均数量和生物量密度分别为(26 806±39 968)尾·n mile–2和(403.68±601.9)kg·n mile–2、(34 416±38 497)尾·n mile–2和(124.5±139.26)kg·n mile–2。统计分析结果显示,2014年秋季渔获组成单一和混合2种不同条件下,调查海域渔业资源数量与生物量密度均存在显著性差异(P=0.007<0.05;P=0.004<0.05);而2015年春季不同条件下差异均不显著(P=0.113>0.05;P=0.310>0.05)。该差异可能与不同季节声学评估种类优势集中程度相关。由于鹿斑鲾(Secutor ruconius)等种类季节性集群活动的影响,调查海域渔业资源在水平空间上分布极不均匀。此外,以15m水深为界,不同季节回波单体目标强度(TS)频率组成及其在垂直方向上的分布存在明显差异。

Based on the acoustics and bottom trawl survey data of fishery resources in the Nan＇ao Island area in autumn 2014 and spring 2015, we analyzed the species composition, dynamic and spatial distribution of fishery resources in that area. The dominant species vaired in different seasons. Priacanthus macracanthus was dominant in autumn and Secutor ruconius was dominant in spring. The average quantity and biomass densities of species assessed by acoustic detection were （26 806±39 968） ind·n mile-2 and （403.68±601.9） kg·n mile-2 in autumn 2014, and （34 416±38 497） ind·n mile-2 and （124.5±139.26） kg·n mile-2 in spring 2015, respectively. Significant difference existed in the quantity and biomass density of fishery resources （P=0.007〈0.05; P=0.004〈0.05） in single or mixed-fish species captured in autumn 2014. However, the difference in spring 2015 was not significant （P=0.113〉0.05; P=0.310〉0.05）. The difference might be affected by the degree of dominance of the species assessed by acoustics in different seasons. The horizontal distribution of fishery resources was dramatically asymmetrical due to the seasonal schooling behavior of fish species like S.ruconius et.al. Furthermore, variation of TS （target strength） frequency and vertical distribution of single echo detection were obvious in different seasons with the depth of 15 m as the boundary.