The SACET (South Atlantic Cetacean) Project is a research and conservation initiative led by the EDMAKTUB Association, dedicated primarily to the study of cetaceans in the South Atlantic Ocean. The project’s first expedition took place in the Gulf of Guinea in 2020. Building on that mission, the upcoming 2025 expedition will return to the region, with a special focus on the marine habitats surrounding the islands of São Tomé and Príncipe.

Primary Objectives

Cetacean Research

Study of the species distribution, habitat use, behaviour, photo-identification, acoustics and morphometrics and body health.

Monitoring other megafauna

Study of sea turtles, sea birds and fish.

Habitat state assesment

Study of the pelagic zone, coastal waters, adjacent inshore waters, coral reefs and mangrove forest.

Monitoring Marine debris

Monitoring the amount of plastics and litter found in the study area.

Collaboration and outreach to local organizations

All the initiatives promoted from this project will have as one of the objectives the participation and collaboration with the local entities working in the area.

The Study Area

The 2025 expedition will set sail from Cabo Verde, along the western coast of Africa, and travel through the Gulf of Guinea to the islands of São Tomé and Príncipe. Throughout the journey, the aim is to collect as much data as possible using a combination of visual observations, acoustic monitoring, and biological sampling. This comprehensive approach is designed to maximize understanding of cetacean presence, behavior, and the overall health of the marine ecosystem along the route.

São Tomé and Principe

São Tomé and Príncipe is a biologically rich tropical archipelago with high cetacean diversity.This initiative aims to assess local marine biodiversity, with a particular focus on cetaceans and other marine fauna. The goal is to address existing knowledge gaps and enhance understanding to support conservation efforts and the sustainable use of the country’s coastal marine ecosystems. Fostering community-driven marine biodiversity management.

Main research methods

Assessment of site fidelity and identification of key areas such as breeding, feeding, and nursing grounds

Humpback whale breeding ground

The occurrence of southern hemisphere humpbacks whales in Sao Tome has been reported since the 19th century. Several studies suggest the presence of humpback whales belonging to the South Atlantic Stock in the tropical waters of the Gulf of Guinea, that serve as breeding ground throughout the summer until late November. Humpback whales groups seem to prefer shallow waters around São Tomé Island and this was observed to be true also for waters around Principe during this study.

Random transects along the study area are being performed to identify the areas of presence of this animals as well as the group composition and main behaviours observed in order to define the use of habitat of each of the encountered species.

Other cetaceans observed in the study area

Pantropical spotted dolphins

Stenella attenuata

False Killer Whale

Pseudorca crassidens

Bottlenose dolphin

Tursiops truncatus

Orca

Orcinus orca

Sperm Whale

Physeter macrocephalus

Recording of vocalizations using towed hydrophone and a sound trap to study acoustic behavior and species presence.

Humpback whale songs

Acoustic surveys using a towed hydrophone are being performed to detect cetacean presence. Being able to detect dolphin wisthles and clicks, sperm whale clicks and codas and humpback whale songs.

Studied through direct visual observations and the analysis of drone footage to document activity patterns, social interactions, and surface behaviors.

The use of drone to study cetacean behavior

Drones have been proven to be a key tool to study cetacean behaviour. Drones offer a new perspective that allows to observe the behaviors that occur close to the surface in a non-invasive way.

Estimation of population size, structure, and composition based on sighting data and drone-based observations.

Combining boat and drone observations to describe the population composition and movements

The data and pictures obtained from the boat and the images obtained with the drone allow us to get an understinding on the group composition and identity.

Photo-identification of Humpback whales

Boat based photo-ID

The humpback whale photo-identification from the vessel can be done by taking pictures of the fluke of the animals when diving or playing on the surface and through lateral dorsal fin pictures.

Drone photo-ID

Flying over the animals focusing on the head region. Checking scars, pigmentation and tubericles of the head.

Evaluation of body condition and health, as well as size determination, using drone photogrammetry.

The use of drone has allowed to get morphometrics and body condition information of humpback whales

Studying the morphometry and body condition of the animals in the area can apport key information about the population health in the area.