黑潮-亲潮交汇区中上层渔获量变动对涡旋的响应

Effects of eddies on catch in mid-pelagic species in the Kuroshio-Oyashio confluence region

摘要:

海洋中尺度过程对渔场空间变动的影响是渔业资源评估的重要内容。为了阐明黑潮-亲潮交汇区（145°E~165°E和35°N~45°N）渔场资源丰度对中尺度涡的响应关系,利用上海海洋大学“淞航”号远洋综合调查船2021—2023年6—8月西北太平洋调查航次中上层拖网渔获产量和卫星高度计数据,研究了渔获密度与环境因子和涡旋的关系。结果显示,海水温度和叶绿素a质量浓度与渔场渔获密度分布在空间上显著相关,二者主导中上层渔场资源丰度,40°N以北海域平均渔获产量较高,40°N以南渔获产量偏低。气旋涡1~2倍半径内叶绿素a质量浓度正异常显著,反气旋涡叶绿素a质量浓度东北部正异常,其余方向均减少；涡旋2倍半径范围内,鱼群更偏向于气旋涡南部和反气旋北部聚集。气旋涡虽然是营养性涡旋,但其伴随的上升流导致水温过低,不利于鱼群聚集。黑潮-亲潮交汇区海洋生物倾向于在气旋涡南部和反气旋涡北部聚集。本研究可为西北太平洋短期的渔情预报和渔场重心预测提供科学依据,而黑潮流轴的年际动态差异引起的渔场变动仍需进一步研究。

关键词:中尺度涡;渔场;资源丰度;环境变化;黑潮-亲潮交汇区

Abstract:

The effect of marine mesoscale processes on spatial variation of fisheries is an important part of fishery resources assessment.In order to clarify the response relationship between fishery resource abundance in the Kuroshio-Oyashio confluence region （145°E-165°E, 35°N-45°N） and mesoscale eddies, this study utilized data from mid-pelagic trawl catches and satellite altimetry collected during research cruises in the Northwest Pacific from June to August 2021-2023 by the "Songhang" of Shanghai Ocean University research vessel. The study investigated the relationship between catch density and environmental factors as well as eddies.The results indicate a significant spatial correlation between sea surface temperature, chlorophyll-a mass concentration, and the distribution of fishing density in the fishing grounds. These factors predominantly influence the resource abundance of middle and pelagic fishery. The average fish catch yield is higher in the sea area north of 40°N compared to those south of it. Within 1-2 times the radius of cyclonic eddies, there is a notably positive abnormality in chlorophyll-a mass concentration. Conversely, in anticyclonic eddies, there is a positive abnormality in chlorophyll-a mass concentration in the northeastern part and reduced mass concentrations elsewhere.Within a radius of two times the eddy, fish aggregation was favored to the south of the cyclonic eddy and to the north of the anticyclone. Although the cyclonic eddies are nutrient eddies, their accompanying upwelling leads to low water temperatures, which are not favorable for fish aggregation. Marine organisms in the Kuroshio-Oyashio confluence region tend to aggregate in the southern part of the cyclonic eddy and the northern part of the anticyclonic eddy.This study can provide a scientific basis for short-term fishery forecasting and prediction of the center of gravity of the fishery in the Northwest Pacific Ocean, while the fishery changes caused by the inter-annual dynamic difference of the Kuroshio Current axis still need to be further investigated.

Key words:mesoscale eddy;fishing grounds;resource abundance;environmental change;Kuroshio-Oyashio confluence region