The fishermen ecological knowledge (FEK) encompasses information on biology of species and climatic and oceanographic changes, all related with schools of fish and its capture. It incorporates a complex set of codes and signs, which are constantly updated and transmitted orally thorough generations. In this sense, FEK presents characteristics such as diversity and ability to learn from experience, which are in conformity with the definition of a complex adaptive system (CAS). Based on this assumption, this work proposes to structure and interpret FEK as a CAS. It is supported that such approach can promote the exchange of information among areas, which are other way considered incommensurable (anthropology, oceanography, marine biology, meteorology etc.), and also among formal sciences and the FEK. However, CAS is a structure designed with heuristic goals associated with mathematical modeling what is beyond the aims of this work, which uses CAS only as a structuring metaphor.