The aim of the present study is to describe the main milestones of the Spanish purse seine fishery targeting on tropical tunas in the Indian Ocean, since the first fishing prospecting survey in the 1980s to the present. We also review the scientific effort that has been done for this period to obtain reliable scientific fishing estimations. Finally, the current situation of this fleet is described, after the economic crisis of this last decade. All these milestones are important to understand some peak and down in the historical data series from Spanish tropical tuna catches, and scientific estimations.