Evaluation of the Sustainability of Marine Resources in the Reef Areas of Furong Island Marine Ranching Based on the Ecopath Model

Marine ranching is a crucial component of the “blue granary” strategy. Evaluating the long-term conservation effectiveness of artificial reef areas in marine ranches helps to assess the current conservation status, identify issues during the conservation process, and develop targeted solutions. Based on survey data from the national marine ranching in the western waters of Furong Island in 2019 and 2022, we used Ecopath with Ecosim version 6.7 to construct Ecopath models for the two periods. By comparing factors such as trophic structure, system attributes, and energy flows, we evaluated the potential ecological effects associated with sustained conservation and management activities. The results indicated that the trophic level structures of the ecosystem food web between 2019 and 2022 were similar. The trophic levels of most functional groups in 2022 were slightly higher than those in 2019, and the biomass increased significantly. The biodiversity slightly increased, with the Shannon index rising from 1.544 to 1.570, and the trophic levels of most functional groups increased. The overall ecosystem scale expanded by 29.37%, while total primary production/total respiration (TPP/TR), total primary production/total biomass (TPP/TB), and the ascendancy (A) value decreased, and Finn’s cycling index (FCI), mean path length (MPL), and transfer efficiency (TE) increased. Collectively, these changes suggest a tendency toward greater ecosystem maturity, although not all ecosystem indicators exhibited consistent responses. In the energy transfer process, the proportion of energy flowing into each trophic level improved. The detrital food chain dominated the system’s energy supply, though its proportion of total flow decreased from 61% to 57% over the years, while the energy contribution from primary producers increased, and the total transfer efficiency of both pathways improved. Analysis of mixed trophic impacts and keystone species revealed changes in keystone species. Overall, the observed changes from 2019 to 2022 were consistent with potential ecological improvements under sustained conservation and management. These findings will contribute to the further refinement of fisheries resource conservation methods and support decision-making for marine ecosystem restoration.