[A-OS15] Marine ecosystems and biogeochemical cycles: theory, observation and modeling

[AOS15-P06] Effects of oceanographic conditions on fishery distribution: A case study of chub mackerel (Scomber japonicus) in northeastern Taiwan

*Shin-ichi Ito¹, Sandipan Mondal², Ming-An Lee² (1.Atmosphere and Ocean Research Institute, The University of Tokyo, 2.National Taiwan Ocean University)

Keywords:chub mackerel, climate oscillations, ensemble modeling, East China Sea

Oceanographic conditions affect species distribution in marine habitats. Global climate change has also been influencing the species distribution through various climate impact drivers. We assessed the influence of marine environmental factors on chub mackerel (Scomber japonicus) distribution in northeastern Taiwan by constructing and using a habitat ensemble model incorporating chub mackerel fishery from 2014 to 2019, climate oscillation indices, and oceanography data. Our results indicated that the chub mackerel catch was mainly influenced by the Western Pacific Oscillation, whereas the fishery data was limited to 6 years. Sea-surface height (SSH) exerted the most significant effects on chub mackerel distribution. The chub mackerel catch rate peaked in the study area with a SSH of 0.575 m, a sea-surface temperature of 29 °C, sea-surface chlorophyll of 0.25 mg/m³, and sea-surface salinity of 33.7. Fishery catch was predicted from oceanographic data using five single-algorithm models: GLM, generalized additive model (GAM), gradient boosting method (GBM), random forest (RF), and classification and regression tree (CTA). Because GAM, GBM, and RF showed better prediction skills, the ensemble species distribution model was established using the three models. The ensemble model showed better prediction skills and stability than those of the single species distribution models. The ensemble model revealed most wide distribution of chub mackerel in the area between 25°N, 120.5°E and 26.2°N, 121.5°E. Our findings support the feasibility of the ensemble species distribution modelling approaches for critical adaptation planning for fishery managements. Considering changing climate conditions globally, the incorporation of this knowledge into managerial strategies may aid decision-makers in protecting not only other ocean fisheries but also individuals dependent on them. This study has been already published on Marine Environmental Research (https://doi.org/10.1016/j.marenvres.2024.106803).