2026-07-14 東京大学
黒潮大蛇行によるマサバの小型化と資源減少の概念図
＜関連情報＞
- https://www.aori.u-tokyo.ac.jp/research/news/2026/20260714.html
- https://www.sciencedirect.com/science/article/pii/S0079661126001187
黒潮の大蛇行が2018年から2024年にかけて北西太平洋におけるマサバ（Scomber japonicus ）の成長、分布、加入に及ぼす影響 Impacts of Kuroshio large meander on growth, distribution, and recruitment of chub mackerel (Scomber japonicus) during 2018–2024 in the Northwestern Pacific
Ziqin Wang, Shin-ichi Ito
Progress in Oceanography Available online: 22 June 2026
DOI:https://doi.org/10.1016/j.pocean.2026.103784
Highlights
- Coupled growth-population model reproduced chub mackerel decline in Kuroshio LM.
- Kuroshio LM caused reduced chub mackerel growth and recruitment due to low food.
- LM shifts early life stages to poor areas, limiting access to high feeding grounds.
- Reduced food availability influenced the recruitment of the January–April cohorts.
- Transportation was the primary driver for the May–June cohorts.
Abstract
The Kuroshio is uniquely distinct among western boundary currents. A direct connection between the 2018–2024 Kuroshio large meander (LM) and the chub mackerel population dynamics remains unconfirmed. In this study, we developed a coupled growth-population dynamics model incorporating a super-individual movement module to investigate the effects of the Kuroshio LM on the growth and recruitment of age-0 chub mackerel. The model successfully reproduced the ontogenetic migration pattern under climatological environmental forcing and was then applied to the 2018–2024 period, which coincided with the longest recorded LM event. Simulation results indicated that year-classes born during LM years exhibited lower daily growth and survival rates than those born during non-LM (nLM) years. Sensitivity analyses revealed that sea surface temperature in LM years was optimal for recruitment, whereas food conditions and sea surface current fields under the LM regime reduced the survival of chub mackerel. Environmental effects varied with the spawning season; food availability was the dominant constraint for cohorts from the non-main spawning season (January–April), whereas the sea surface current field strongly influenced cohorts from the primary spawning season (May–June). Further analysis revealed that the influence of the current field on the main spawning season was attributable to the direct effects of LM as well as the flow field in the spawning ground directed toward the Kuroshio axis. Our findings highlight the cohort-specific vulnerability of chub mackerel to oceanographic anomalies and demonstrate the necessity for an integrated understanding of timely adaptive management against extreme events.
