Hunting and invasive species are amongst the main causes of species extinctions on oceanic islands. On the island of São Tomé hunting of introduced mammals (monkeys, civets and pigs) and endemic bird species has contrasting effects in terms of conservation. Hunting of introduced mammals may benefit native fauna and flora but pressure on endemic birds poses a threat to some species. We conducted semi-structured interviews with 119 hunters to assess the relative importance of native and introduced prey species, gathering information on personal profiles, preference and practice, and hunters’ perceptions of trends in prey populations. Eleven species were hunted, including five invasive mammals and five endemic birds of high conservation importance. Based on species hunted, techniques used and final destination of the quarry we distinguished three groups of hunters, using cluster analyses: bird, monkey and feral-pig hunters. Bird hunters were all from urban areas but most pig hunters were rural. Monkey hunters were mostly rural workers but a small proportion were from urban areas. Bird and monkey hunters were primarily motivated by commercial gains but they also hunted for enjoyment and food. In general, hunting of mammals is an opportunistic activity that, if regulated, can be sustainable and contribute to mitigating the effects of invasive species on local fauna as well contributing to local livelihoods. Given the economic drivers involved in hunting of birds, intervention to reduce or eliminate this form of hunting will require enforcement of legislation and raising awareness of the issues involved.

The Atlantic species of the alpheid shrimp genus Parabetaeus, P. hummelincki, is reported for the first time from São Tomé in the Gulf of Guinea, and Cozumel off Mexico's Yucatan Peninsula. These records extend the distribution range of P. hummelincki into the tropical eastern Atlantic and western Caribbean Sea, making this species amphi-Atlantic and the genus Parabetaeus fully pantropical.

Killer whales Orcinus orca are considered to be relatively uncommon in tropical waters. Few sightings have been reported from the west coast of Africa due to a paucity of survey coverage. We present data on 32 killer sightings from tropical waters off Angola (N = 18), Gabon (N = 7), São Tomé (N = 6) and Cameroon (N = 1), comprising a combination of dedicated survey sightings (N = 21) and reliable anecdotal records (n = 11). Killer whales were reported from coastal waters, the shelf edge and deep, oceanic areas. Sightings indicate a probable year-round occurrence of killer whales within the region. Mean group size was 5.6 animals. There was no difference in group size between sightings in waters >200 m deep and those on the continental shelf. No photo-identification matches were found between Angola, Gabon and São Tomé. Re-sightings of two individuals occurred annually in São Tomé during 2002–2004. Killer whales had external appearance consistent with the Type A nominate species form. Antagonistic encounters were recorded between killer whales and humpback whales Megaptera novaeangliae off Angola, Gabon and Cameroon, and with sperm whales Physeter macrocephalus off Angola. Predation on ocean sunfish Mola mola was recorded in São Tomé, and possible predation on sharks was recorded twice in Gabon.

São Tomé and Príncipe is an archipelago located in the Gulf of Guinea. This archipelago seems to be an important area for cetaceans, probably due to large concentrations of prey, as well as the existence of several small bays and shallow water that constitute preferred rest areas. In comparison to other areas of the world, little is known about cetacean communities in this archipelago. Boat-based surveys to record sightings of cetaceans were conducted between 2002 and 2005, which represents the first approach to study the occurrence of whales and dolphins in this tropical region. Sightings of humpback whales (Megaptera novaeangliae), bottlenose dolphins (Tursiops truncatus), pantropical spotted dolphins (Stenella attenuata), killer whales (Orcinus orca), sperm whales (Physeter macrocephalus) and pilot whales (Globicephala melas) were recorded. Cetaceans were found throughout a range of sea surface temperature between 24 and 29°C and a wide range of depths. Significant differences were found regarding the occurrence of some species. Humpback whales showed a preference for shallower waters between 20 and 100 m. Bottlenose dolphins occurred most commonly along the continental shelf (20 to 100 m) and pantropical spotted dolphins occurred in deep slope waters (>1000 m).