Its obvious that it is necessary to understand a given system if one wishes to effect desired changes within it. If human beings compose one of the units within the system, and if their actions are necessary to effect the desired changes, then it is essential to understand their perceptions of effected elements within the system. With regard to changes in small-scale fisheries, it is important to note that local fishermen have usually been interacting with the sea for a long time. In their attempts to cope with the sea, they have made inferences from their observations and constructed taxonomies and theories concerning the marine environment and its flora and fauna. This folk science, or ethno-oceanography, is as real and important to the local fisherman as theories concerning ocean systems are to the academic oceanographer. Thus, attempts to communicate information concerning the ocean must take these folk scientific systems into account.