Grant Geophysical Inc. performed 2-D seismic surveys in transition zones on the coast of Bahia State, Brazil, from January to May 2002. The surveys were conducted between Boipeba Island and Barra Grande Beach (Figure 1), where depths range from 12 to 55m. During seismic activities, the occurrence of cetaceans was detected in the surveyed area. The aim of this note is to report sightings of all species of dolphins recorded during seismic surveys conducted in the region.In order to obtain the appropriate license to operate in Brazilian waters, seismic surveying companies are required by the Brazilian Institute for the Environment and Natural Renewable Resources (IBAMA) to carry out an environmental monitoring program while seismic activities are being conducted. This program was subdivided into two parts, marine and terrestrial monitoring. Marine monitoring consisted in recording the occurrence of marine organisms from two distinct boats, the gun boat (GB) and the environmental monitoring boat (EMB). The GB was responsible for shooting four 2200-PSI airguns (one shooting cycle/16s) and had a permanent observer on the top of its cabin, who tried to record the presence of those organisms when airguns were either turned on or off ('blind' observation). The EMB had no seismic source onboard; however, an observer was present, with the role of monitoring the operation boundaries to record the presence of marine organisms. Each observer was equipped with a pair of reticule binoculars (red-lens compact Bushmaster 10x25mm) in order to improve his sightings. The GB observer was obligated to stop the seismic surveys whenever either a cetacean or a sea turtle was detected less than 500m far from the seismic source of the GB (the safety zone was arbitrarily estimated by the observer). While the operation was set, for example, as cables were being deployed, the EMB moved away from the surveying site to record the occurrence of marine organisms in the vicinity and/or to place a third observer on land, who was responsible for monitoring the coastline. Once airguns started working, no boat, except the GB, could have its engine on near the surveying site, to avoid interference with the seismic data registering process (performed by a third boat, which recorded the information obtained through the sound-wave reflection on the sea bottom). Hence, the EMB had to keep a distance of at least 1.0nm (ca 1.8km) from the shooting line during seismic surveys.Approximately 6km of coastline were surveyed daily, in searching for stranded animals. The position of the airgun shooting line was taken into account to establish the area that would be roamed, and whenever a line was completed, the monitored area changed following the location of the next line to be shot. As strandings were not expected to occur immediately after the GB operation, there was an overlap in the monitored areas in order to optimize monitoring efforts. Thus, one specific site could be monitored during subsequent days after the conclusion of the corresponding shooting line....