Modeling distribution of Hexagrammos otakii in Haizhou Bay based on spatio-temporal species distribution models

To understand the spatio-temporal distribution characteristics of Hexagrammos otakii in Haizhou Bay and its influencing factors, a spatio-temporal species distribution model was constructed based on the bottom trawl fishery resource surveys and environmental observation data conducted in Haizhou Bay from autumn 2013–2019 and used to analyze the relationship between its distribution and environmental factors. The residual independence and heterogeneity of the model were compared with those of the generalized additive model (GAM) by residual analysis, and the prediction performance of the model was tested by cross-validation, and finally the distribution was predicted and the habitat suitability index (HSI) and the center of gravity of resource distribution were calculated by the delta method. The deviation explanation rate of the spatio-temporal model was 65.50%, and model analysis showed that the most important environmental factor influencing the distribution of H. otakii was water depth (22.11%), followed by bottom water temperature (12.98%), while bottom salinity (0.09%) had less influence. There was a positive correlation between water depth and its distribution, a negative correlation between bottom water temperature and its distribution, and a weak positive linear relationship between bottom salinity and its distribution. The residual independence and heterogeneity of the spatiotemporal model was stronger than that of GAM, with a cross-validation regression line slope of 0.90±0.38. The model predictions showed that H. otakii mainly distributed in the sea area north of 34.5°N and east of 120.0°E. its high HSI value area tended to shrink year by year, and the center of gravity of resource distribution was shifting to the northeastern sea area, which might be the result of the combined effect of climate change and fishing pressure. This study analyzes the spatio-temporal distribution of H. otakii in Haizhou Bay, which is important for understanding the distribution dynamics of H. otakii and scientific fisheries management.