Numerical Analysis and Modeling of the Yangtze River Fish Ecosystem in Nantong: The Impact of Human Intervention

Abstract

This study develops a systematic mathematical framework to analyze fish population dynamics in the Nantong section of the Yangtze River under various forms of human intervention, including fishing bans and pollution control. Drawing on multi-year data (2017–2023) of fishery stock assessments, pollution discharge, and water quality indicators, two core models—the Lotka-Volterra competition model and a population growth with environmental carrying capacity model—were employed to simulate species interactions and habitat changes. Parameter estimates were calibrated using observed variations in key fish populations (e.g., Chinese sturgeon, silver carp) and ecosystem conditions, integrating factors such as fishing mortality rates and pollutant-induced mortality. Numerical simulations reveal that high competition coefficients (e.g., silver carp exerting significant pressure on sturgeon) and heightened mortality from fishing or pollution markedly reduce sturgeon stocks. In contrast, bans on fishing and reducing pollution sources effectively raise carrying capacities and promote resource recovery. These findings underscore the importance of policy interventions in balancing conservation efforts with sustainable fishery practices. The proposed modeling approach enriches ecological research on the Yangtze River and provides decision-makers with actionable insights into the design and assessment of conservation strategies.