<p>Marine ranch is a novel paradigm in the transformation of traditional fisheries, which embodies a modern and high-tech approach to increasing marine fishery production and enables the sustainable and efficient exploitation of marine resources. After several decades of development, the industrial model of marine ranch has matured. However, in several developing countries, subsequent management and evaluation remain inadequate. In this study, the Dachen Island Marine Ranch in the East China Sea was used as a case to explore two fishery management strategies. A multi-species size spectrum model (MSSM) was established for the Dachen Island Marine Ranch to simulate fish community dynamics. While considering interspecific interactions, the effectiveness of two management strategies was assessed: (1) altering fishing mortality; and (2) increasing cod-end mesh size. The findings indicate that the change in the fishing mortality of large predators can induce trophic cascade effects, and the large predators have the greatest impact on community structure. In scenarios that simulate fishing mortality for multiple species, competition is shown between two species occupying similar ecological niches. An increase in cod-end mesh size can be observed to decrease bycatch while positively impacting community structure. Our findings suggest that fisheries management reforms should consider the effects of management changes on the entire ecosystem (including environment and biodiversity), rather than concentrating solely on the long-term yield of fish harvests. A stable ecosystem can yield more products, and long-term sustainable fishery yields are one of them.</p>