Game-Theoretic Analysis and NetLogo Simulation of “Ten-Year Fishing Ban” Enforcement in Yangtze River: A Case Study of the Poyang Lake

[Objective] The “Ten-Year Fishing Ban” is a critical ecological conservation strategy designed to restore the Yangtze River ecosystem in China. However, its implementation and management have been hindered by persistent challenges and recurrent issues. Taking Poyang Lake as a case study, this study integrates field investigations with NetLogo to simulate enforcement dynamics. It further explores the impact of strategy probability combinations, levels of economic penalties, and land-water patrol resource allocation on enforcement effectiveness, aiming to provide insights for long-term management strategies of the fishing ban. [Methods] This study employed a game-theoretic framework, constructing a payoff matrix to model the strategic interactions between law enforcers and poachers. Nash equilibrium solutions were derived from field data and government statistics to inform resource allocation strategies for subsequent multi-agent simulations. Key policy variables, including the apprehension frequency, levels of economic penalties, and the ratio of terrestrial to aquatic enforcement resources, were evaluated through parameter sensitivity analysis. [Results] (1) the probability distribution of different law enforcement strategy combinations significantly influenced the intensity of illegal fishing activities. Intelligent surveillance was identified as a critical tool for the long-term management of the fishing ban. The simulation also reflected common poacher tactics, including equipment upgrading, coordinated operations, and exploitation of familiar fishing areas. Consequently, local enforcement should rely primarily on high-tech intelligent surveillance, supplemented by manual patrols and public education, with an apprehension frequency exceeding 0.41 to effectively deter illegal fishing. (2) Both the levels of economic penalties and the apprehension frequency exerted a suppressive effect on poaching activities, with the apprehension frequency demonstrating a more pronounced impact. Moreover, a clear substitution effect between these two factors was observed: in terms of enforcement effectiveness, increasing the apprehension frequency by 0.01 was equivalent to raising economic penalties by 2 000 yuan, approximately 0.07 times the illegal gains. Therefore, imposing high economic penalties and maintaining a high apprehension frequency were confirmed as primary measures to deter illegal fishing. Specifically, economic penalties must exceed 1.53 times the illegal fishing income to effectively deter violations. Moreover, increasing the apprehension frequency (even through verbal warnings and education) was found to exert a stronger deterrent effect than imposing economic penalties. (3) Analysis of optimal enforcement efficiency revealed that, regardless of whether a high economic penalty or a high apprehension frequency strategy was adopted, 84%-86% of law enforcement resources should be allocated to shoreline areas. This was attributed to the complex topography of the shoreline, which limited the effectiveness of technical surveillance and increased the difficulty of manual patrols. This allocation recommendation also aligned with empirical observations that productive poaching in open waters had decreased significantly since the fishing ban, while illegal fishing activities along the shore had continued to increase. [Conclusions] To ensure the long-term maintenance of the fishing ban, the following key strategies are proposed. (1) Enhanced intelligent surveillance: integrating drones, satellite remote sensing, radar, and optoelectronic thermal imaging to establish a 24/7 all-weather surveillance network is recommended. (2) Optimized penalty-prevention mechanisms: scientifically adjusting penalties based on violation severity, frequency, and ecological impact is proposed, aiming to address the issues of low-cost and recurrent illegal fishing. Innovative and diversified punitive measures that combine participatory education (e.g., mandatory community patrols) and deterrent sanctions (e.g., ecological restoration through fish stock enhancement) should be implemented to raise ecological awareness and enhance compliance among fishermen. (3) Cross-sector collaborative governance: a multi-jurisdictional data-sharing platform should be developed, and violation heatmaps should be utilized for precise allocation of enforcement resources. Interagency coordination among water administration, public security, and market regulatory agencies must be strengthened to establish a tiered and efficient regulatory framework. Furthermore, regional cooperation across city, town, and village levels should be enhanced, informed by international fishery management practices, and regular fishery resource surveys should be institutionalized.