Relationship between nautical area scattering coefficient and environmental factors in the southern marine ranching area of Beihai, Yintan

This study investigated the relationship between fishery resources and environmental factors in the Beihai marine ranching area. Four consecutive years (2021–2024) of acoustic transect surveys were conducted in the southern part of the Beihai Yintan National Marine Ranching Demonstration Zone in Guangxi. Simrad EK80 (120 kHz) and EY60 (200 kHz) scientific echosounders were used to collect Nautical Area Scattering Coefficient (NASC) data, while hydrological, water quality, and heavy metal parameters were simultaneously measured. Acoustic signals were processed using Echoview software for standardized analysis. Principal component analysis, correlation analysis, and random forest modeling were then applied to systematically explore the spatiotemporal response patterns of fishery resources under a multi-factor environmental framework. The results revealed that the composite principal component of water temperature and active phosphate was significantly correlated with fishery resources from 2022 to 2024, with the direction of correlation shifting from negative to positive. Among the heavy metals, lead (Pb) consistently emerged as the most influential variable across all surveyed years. This result indicates a stable and significant impact of Pb on the acoustic distribution of fish and identifies it as a key environmental driver of resource fluctuations. This study confirms the applicability of acoustic technology in ecological assessments and expands the theoretical understanding of interactions between fisheries acoustics and environmental factors. The findings provide valuable scientific support for the dynamic management and multi-factor regulation strategies of marine ranching.