Today, fishing villages are facing the risk of extinction, which underscores the necessity of rural fisheries business as a strategy for their survival. This study explores perceptions of rural fisheries business among Ochongye and examines how external openness and attitudes toward government support influence the relationship between its perceived necessity and the intention to engage in joint business activities. Mediation analysis indicates that the perceived necessity of rural fisheries business (e.g., securing new labor) positively affects the intention to pursue joint activities (e.g., attracting external capital), and this effect is partially strengthened through external openness (e.g., in-migration of outsiders, expansion of Ochongye membership). In contrast, moderation analysis shows that external openness does not significantly moderate this relationship, whereas attitudes toward government support function as an important moderating factor.