In the southwest Atlantic Ocean, the catches of yellowfin tuna (Thunnus albacares) are relatively high, but skipjack tuna (Katsuwonus pelamis) is the target species. However, due to the high market value, fishermen have been interested in trying to increase the yellowfin catches and yields in the southeast and south Brazil. In order to gather information to improve yellowfin fishery we analyzed the spatio-temporal variations of the fishing patterns (effort, catch and CPUE) off Brazil. The preliminary results obtained suggest that the vulnerability of yellowfin tuna is large all over the traditional baitboat fishing ground off Brazil. However, the profits are especially high in the second quarter and in south (southward of 30°S). Furthermore, aggregating devices (e.g. oilrig platforms and drifting or anchored buoys) proved to enhance yellowfin tuna yields.