Impact of climate change on the distribution of Trachurus japonicus in the Northern South China Sea

Understanding the impact of climate change on the distribution of marine species is of vital importance for the sustainable development of marine fisheries. In this study, an ensemble species distribution model is employed to predict the potential distribution of Japanese jack mackerel (Trachurus japonicus) in the Northern South China Sea (NSCS) under current conditions and three future climate scenarios (IPCC Representative Concentration Pathways RCP126, RCP245, RCP585). The model incorporates vital environmental variables including sea surface salinity (SSS), sea surface height above geoid (SSH), sea surface temperature (SST), ocean mixed layer thickness (MLD), and distance from land (DFL). Notably, SST and SSH are found to be the most influential factors in defining the habitat of T. japonicus. Model predictions reveal that the current suitable habitats for T. japonicus are primarily located in the offshore area to the west of the Pearl River estuary, especially in waters with depths of less than 100 m in the NSCS. The Beibu Gulf emerges as a prominent habitat for this species. However, projections indicate a significant reduction in areas with a high probability of T. japonicus occurrence, particularly in scenarios with high emissions. This reduction in suitable habitats is primarily observed in the NSCS at depths ranging from 40 to 100 m, while the northwestern coastal regions of the NSCS are projected to witness an increase in suitable habitats. The rate of habitats contraction is expected to surpass that of expansion, with an estimated 16.93 % to 29.27 % decrease in suitable habitats by 2091-2100.These findings offer fundamental insights into how climate change impacts the distribution of T. japonicus in the NSCS and provide valuable guidance for future resource development and utilization.