From dynamics to sustainability: Modeling the shrimp (Penaeus chinensis) fishery in Shandong, China

Since 1984, the stocking of shrimp juveniles has been implemented in the Bohai Sea, China as a strategy to manage the depleted marine fishery. Subsequently, major harvest restriction policies including "Dual Control" (1987), "Summer Fishing Moratorium" (1995), and "Fishermen Transfer and Fishing Fleet Scraping" (2003) were gradually implemented to reduce fishing intensity. However, the relative effectiveness of these three policy changes and management improvements, such as varying stocking quantity, adjusting the duration of the summer fishing ban, and reducing fishing intensity rate have rarely been assessed before their implementation. To address this gap, we developed a System Dynamic model that incorporated multiple scenarios related to these strategies in the shrimp fishery. Using Penaeus chinensis shrimp in the coastal province of Shandong, China, as a test case, we simulated the harvest metrics and stock size for each scenario. Our model predictions revealed that among the three strategies, extending the duration of the summer fishing ban is the most likely to improve the harvest metrics, while reducing fishing intensity significantly increases shrimp abundance. Based on the research findings, we recommend an optimal combination of the three strategies: releasing approximately 700 million individual juveniles per year, decreasing the fishing intensity rate to 0.65, and increasing the duration of the summer fishing ban to 123 days, from 1 May to 31 August. The research outcomes contribute to evidence-based decision-making and sustainable management practices in the Bohai Sea shrimp fishery and beyond.