Temporal and spatial heterogeneity of antarctic krill abundance in relation to seawater temperature

Antarctic krill ( Euphasia superba ) is a keystone species in the Southern Ocean, with seawater temperature playing a crucial role in its distribution and abundance. The relationship between seawater temperature and catch per unit effort (CPUE) of Antarctic krill exhibits both spatial and temporal variability, highlighting the need for a comprehensive analysis to unravel these patterns. To address this issue, we employed multiple models, including Ordinary Least Squares (OLS), Geographically Weighted Regression (GWR), and Geographically and Temporally Weighted Regression (GTWR) with one time factor or two time factors. Results indicated that the GTWR model incorporating two time factors outperformed other models in terms of goodness-of-fit, demonstrating a more balanced residual distribution across both space and time. The analysis revealed that the influence of seawater temperature on CPUE exhibited significant variability across different temporal and spatial contexts. Specifically, in the fishing ground located north of 62°S and east of 56.5°W, a predominantly positive correlation between seawater temperature and CPUE was observed. In contrast, other regions exhibited both positive and negative correlations, underscoring regional differences in the influence of seawater temperature. Temporally, the study identified distinct patterns: seawater temperature coefficients were primarily positive in 2015, followed by a downward trend that turned negative by 2020. Seasonal variations were also evident, with positive coefficients predominantly occurring during May and June, while other months showed a more balanced distribution of positive and negative coefficients, highlighting distinct seasonal dynamics. This research provided a scientific foundation for the management and sustainable development of Antarctic krill resources, offering valuable insights for more accurate assessments and management strategies concerning fishery resources.