中尺度涡与海冰对斯科舍海南极磷虾拖网CPUE的影响

Effects of mesoscale eddies and sea ice on trawl-survey CPUE ofEuphausia superba in Scotia Sea

  • 摘要: 南极斯科舍海受南极绕极流驱动,中尺度涡活动频繁,是南大洋典型的涡旋活跃海域。南极磷虾 (Euphausia superba) 作为极地生态系统的关键物种,在此高度聚集并形成全球最重要的商业渔场,但中尺度动力过程与海冰条件对其资源空间分布的调控机制尚不清晰。本研究采用卫星追踪的涡旋轨迹、海冰密集度数据及磷虾拖网渔业数据,分析中尺度涡空间分布与属性特征以及海冰空间格局,通过构建广义加性模型,探究涡旋发展阶段、渔业点到最近涡心的相对距离、海冰密集度及作业经纬度等因素对磷虾单位捕捞努力量渔获量 (Catch per unit effort, CPUE) 的影响。结果表明,斯科舍海中尺度涡呈带状聚集分布,气旋涡数量略多,而反气旋涡空间尺度更大。海冰分布由东南向西北递减。磷虾CPUE在研究海域北侧随纬度升高显著上升,但经向变化不明显。涡旋发展阶段、渔业点到最近涡心的相对距离及海冰密集度对磷虾 CPUE 影响显著。反气旋涡环境中,CPUE随海冰密集度的增加显著下降,高值区集中于低海冰密集度区域;气旋涡环境下CPUE则展现出较强的生境稳健性,重心向中低等海冰密集度及中等相对距离范围偏移。本研究阐明了涡旋动力过程与海冰条件对磷虾空间分布的共同调控作用,可为极地渔场识别及资源管理提供科学支撑。

     

    Abstract: Driven by the Antarctic Circumpolar Current, the Scotia Sea is characterized by frequent mesoscale eddy activity and is one of the most active eddy regions in the Southern Ocean. Antarctic krill (Euphausia superba), a key species in the polar ecosystem, is highly concentrated in this sea area, forming one of the world’s most important commercial fishing grounds. However, the regulatory mechanism of mesoscale dynamic processes and sea ice conditions on the spatial distribution of krill resources remains unclear. Based on satellite-derived eddy tracks, sea ice concentration data and krill trawl fishery data, we analyzed the spatial distribution and characteristic properties of mesoscale eddies as well as the spatial pattern of sea ice. A generalized additive model was established to explore the effects of eddy evolutionary stage, relative distance from fishing locations to the nearest eddy center, sea ice concentration, and fishing longitude and latitude on catch per unit effort (CPUE) of Antarctic krill. The results showed that mesoscale eddies in the Scotia Sea present a zonal aggregation pattern. Cyclonic eddies are slightly more numerous with stronger dynamic intensity, while anticyclonic eddies have larger spatial scales. Sea ice concentration displayed a decreasing gradient from the southeast to the northwest. In the northern study area, krill CPUE increased significantly with rising latitude, while its longitudinal variation was insignificant. Eddy evolutionary stage, relative distance to eddy center, and sea ice concentration exerted significant effects on krill CPUE. Within anticyclonic eddies, CPUE declined markedly with the increase of sea ice concentration, with high-CPUE areas concentrated in low sea ice concentration regions. In cyclonic eddies, krill CPUE showed strong habitat stability, and its distribution centroid shifted toward moderate sea ice concentration and medium relative distance ranges. This study clarifies the joint regulation of mesoscale eddy dynamics and sea ice conditions on the spatial distribution of Antarctic krill, providing scientific support for polar fishing ground identification and fishery resource management.

     

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