In the coastal fishery in Japan, fishermen have solved problems by mutually cooperating and creating agreements under the common law. This main structure of the problem-solving has not changed. Now, however, problems have become too complicated and too uncertain to solve by fishermen alone and so that collaboration among stakeholders is required. This paper aimed to explain the problem-solving process in the coastal fishery, and to clarify the relationship between fishermen and public administration, stakeholders in this process by examining the two cases of sandfish resource management in Akita Prefecture and the brand building of "SEKIAJI SEKISABA" at Saganoseki-cho in Oita Prefecture as successful collaboration between fishermen and public administration, focusing on knowledge creation in the process .
From the two case studies, moreover, this paper presents the process and actor models of problem-solving as theoretical implications and three practical implications: (1) benefits of knowledge creation; (2) the importance of dialogues among stakeholders; (3) the utilization of practical and scientific knowledge.