ABSTRACT Maritime clusters are conducive to promoting the development of an urban economy and maritime industry. The development of high value-added maritime industry is beneficial to upgrading a maritime cluster and improving its competitiveness. We discuss the symbiosis between ports and various value-added industries within a maritime cluster from a resource perspective, using the theory of life cycle and value chain, in order to answer the question: what role does the port play in the upgrading of maritime clusters? An empirical analysis of Dalian, China, was conducted using the Lotka-Volterra model. Our results show that resources were attracted by ports to promote the shipping industry and marine insurance in the non-decline period (NDP) of the cluster. During the declining period (DP) of the cluster, port development led to intensified resource competition and lock-in effects, destabilizing the relationships within maritime industries. Strengthening inter-industry cooperation, increasing market openness, and granting supportive policies to enterprises may rectify this decline. This study provides a reference for managers and researchers to aid in promoting the coordinated development and upgrade of maritime clusters.