The present work brings information about the first sightings of the bottlenose dolphin, Tursiops truncatus, in the oceanic island of Trindade, 1140 km off the Brazilian coast. Nine days of opportunistic boat surveys were performed between December 2009 and March 2010, totalling 54 hours of sampling effort. Three sightings were obtained of the bottlenose dolphin, varying from 1 single animal to a group with 10 dolphins, including calves. One group was observed and filmed underwater. Sighting depth varied from 5 to 35 m and distance from the coast was registered between 70 to 300 m. Comparing our results with other studies in the Brazilian oceanic islands shows similarities in the location of the sightings as well the reported group size and the presence of calves suggesting that bottlenose dolphins may be using these environments to socialize and take care of the young dolphins. Because the oceanic islands constitute fragile and isolated ecosystems it is crucial to have a better understanding of the conservation of their marine life, including top predator animals such as the bottlenose dolphins.

Events of mass mortality of marine fish have been reported to occur world wide, mainly in coastal regions of continental shelves. Here we report an event at Trindade Island, located 1160 km from the Brazilian coast. Melichthys niger was the species most commonly seen affected. Twenty-four other species were found washed ashore. Victims were demersal (72% of species), pelagic (20%) and benthonic species (8%), comprising eight trophic categories. There is evidence that fish kills have occurred at Trindade since at least the 1990s. Mortality events mainly involving primarily Balistidae (Trindade, Maldives and Ascension), Chaetodontidae (St Helena) and Serranidae (Ascension) have been reported for other isolated oceanic localities with low human occupation. It is possible that blooms of toxic algae, under certain conditions cause cascading intoxication along the trophic web. A second hypothesis is that seasonal upwelling events of anoxic or hypoxic waters may be implicated.