Ocean Lab

Scientific Name: Tursiops truncatus (Montagu, 1821)

Common Name: Common bottlenose dolphin.

Classification: Odontoceti (toothed whales), family Delphinidae

Physical notes: Up to 4 m and 650 kg, with robust bodies, mostly grey in coloration, and with short, stubby beak. Offshore ecotypes are usually bigger and darker in colouration compared to inshore sub-populations.

Distribution and habitat use: Most tropical and temperate waters worldwide. Primarily coastal species, including estuarine habitats, but can be also found in pelagic offshore waters and continental shelf waters, especially along the shelf break. It is a resident species, found all year round in Sagres.

Group size: Normally seen in groups less than 15 individuals. But sometimes it can gather in groups of hundreds. Pod composition is relatively fluid, but usually segregated by gender, age, family bond, and reproductive condition.

Life span: 20-50 years.

Gestation period: ca. 12 months. Calves are born ca. 1/3 adult size and they reach maturity at 5 – 15 years. Births take place from May till September. Juveniles are weaned after 18 – 20 months.

Diet and Feeding: Wide variety of schooling fish, cephalopods and crustaceans. Many cooperative feeding techniques used to herd prey. In Portugal, they tend to feed behind trawlers often depredating prey from fishing nets. They can dive up to 500 m and hold their breath up to 12 min.

Typical Behaviour: Not as social with the boats as common dolphins, especially when they feed, as they usually perform deeper dives to search prey on the bottom of sea. If in the mood, they can get very interactive with boats, frequently performing bow and wake riding, and variety of acrobatic leaps. Bottlenoses can jump up to 6 m above sea surface.

Population: Minimum 750 000 worldwide (based on available data). Forecast unknown.

Threats: Suffer habitat degradation, prey depletion, pollution, disturbance from tourism, and by-catch which often lead to death. It is the most hunted species with the purpose to be held in captivity. The main countries that contribute to this are Japan, Russia and United States.

IUCN status: Least concern for overall species worldwide (2018), including Portugal (2023). The Mediterranean sub-population Vulnerable (2009).

Carwardine, M. (2022). Whales, Dolphins and Porpoises. Bloomsbury Wildlife. London, United kingdom.

Ferreira, M., Eira, C., López, A., & Sequeira, M. (2023). Tursiops truncatus roaz. In Mathias, M. L. (coord.), Fonseca, C., Rodrigues, L., Grilo, C., Lopes-Fernandes, M., Palmeirim, J. M., Santos-Reis, M., Alves, P. C., Cabral, J. A., Ferreira, M., Mira, A., Eira, C., Negrões, N., Paupério, J., Pita, R., Rainho, A., Rosalino, L. M., Tapisso, J. T., & Vingada, J. (eds.): Livro Vermelho dos Mamíferos de Portugal Continental. Fciências.ID, ICNF, Lisboa.

Shirihai, H.  (2006).  Whales, Dolphins and Seals: A Field Guide to the Marine Mammals of the World.  Bloomsbury Wildlife. London, United Kingdom.

Still, R., Harrop, H., Stenton, T., & Dias, L. (2019). Europe’s Sea Mammals Including the Azores, Madeira, the Canary Islands and Cape Verde: A field guide to the whales, dolphins, porpoises and seals. Princeton University Press.