This report summarizes data collected for the NOAA Fisheries’ Protected Resources Division in support of its efforts to analyze the potential economic effects of regulating human interactions with wild spinner dolphins (nai'a or Stenella longirostris) in the Main Hawaiian Islands (MHI). Collection and compilation of economic data were undertaken as one component of a comprehensive EIS designed to assess the nature and effects of interactions between spinner dolphins and humans, and the biophysical, socioeconomic, and socio-cultural implications of regulating those interactions. The EIS process is, in this case, being used to facilitate regulatory decisions that achieve balance between the long-term well-being of a protected marine resource and the needs and interests of adjacent human populations. The data that are the primary focus of this report regard economic aspects of spinner dolphin tour operations undertaken in suitable locations in the MHI. Because prospective regulations may directly affect operations which intentionally enable interaction with dolphins, special focus is applied to pertinent economic dimensions of those businesses. Fieldwork and archival research for this project were undertaken between 2006 and 2007. The field research component involved a period of extensive interviewing and observational research with tour guide owner-operators throughout the Hawaiian Islands.