海南东部外海海域鱼类群落结构季节变动及其影响因素

Environmental Influences on Seasonal Variations of Fish Community Structure in Off-sea of Eastern Hainan,Northern South China Sea

【目的】研究海南东部外海海域鱼类群落特征,比较其与近海海域鱼类群落的差异,为海南外海渔业资源的科学管理提供参考依据。【方法】运用群落参数和环境-生物的冗余分析(RDA,Redundancy analysis)研究2019年春季(4月)、秋季(9月)水深86~380 m的海南东部外海海域鱼类群落结构特征。【结果与结论】春、秋季共调查到鱼类312种,隶属于26目96科195属。优势种组成方面,春季为黄鳍马面鲀(Thamnaconus hypargyreus)和深水金线鱼(Nemipterus bathybius);秋季为蓝圆鲹(Decapterus maruadsi)、黄鳍马面鲀、深水金线鱼和短尾大眼鲷(Priacanthus macracanthus);春秋季共有优势种深水金线鱼和黄鳍马面鲀的优势体长存在明显的季节波动,黄鳍马面鲀为秋季(80~105 mm)大于春季(60~85 mm),而深水金线鱼则反之。渔获量季节变化明显,秋季多样性特征指数平均值略高于春季。RDA结果表明,水深、pH、水温、溶解氧和盐度在春、秋季对鱼类资源量(质量密度,kg/km^(2))空间变化的解释率分别为58.34%、53.94%。水深(P=0.003~0.004)和pH(P=0.017~0.002)在春秋季均对鱼类群落结构有显著影响,盐度仅在秋季有显著影响(P=0.013),在春季则无影响(P=0.860)。海南东部外海海域鱼类种类组成、资源量优于海南近海、雷州湾、大亚湾和北部湾海域;在渔业资源开发过程中,除应关注主要经济种类种群水平上的捕捞产量外,更应关注群落水平上种类多样性及优势种的季节变化。

【Objective】To provide basic fishery information for fisheries management in the off-sea of eastern Hainan,the variations of fish communities were studied and compared with those in the coastal waters of the northern South China Sea.【Method】Fish community indices were calculated to reveal the structural characteristics of the fish community,and redundancy analysis(RDA)was applied to quantify the relationship between environmental factors and spatial patterns of fish biomass according to the trawling survey data in the offshore waters of eastern Hainan in April(spring)and September(autumn)2019.【Results and Conclusion】A total of 312 species of fishes were identified,belonging to 195 genera,96 families and 26 orders.Two dominant species occurred in spring and four in autumn,and Thamnaconus hypargyreus and Nemipterus bathybius were the common dominant species.The dominant body-length of Thamnaconus hypargyreus was longer in autumn(80‒105 mm)than that in spring(60‒85 mm),while the dominant body-length of Nemipterus bathybius was shorter in autumn(90‒120 mm)than that in spring(80‒130 mm).The seasonal variations of catches were significant.The averaged values of diversity index were slightly higher in autumn than that in spring.The redundancy analysis revealed that water depth,pH,temperature,DO and salinity contributed to 58.3%of the spatial variations of fish biomass in spring and 54.0%in autumn.Moreover,the water depth and pH were the main factors structuring the fish community in spring and autumn,while salinity was just accounted for the variations in autumn.In conclusion,considering the higher levels of fish species richness and biomass in eastern Hainan offshore waters than coastal waters of Hainan,Leizhou Bay,Daya Bay and Beibu Gulf,more attentions should be paid on the fish community levels in fishery resource management such as variations of the diversity and biomass of dominant species,but not only on the catch of target fish population.