Scientific Name: Balaenoptera acutorostrata (Lacépède, 1804).
Common Name: Minke whale.
Classification: Mysticeti (baleen whales), family Balaenopteridae.
Physical notes: Up to 10m and 9.2t, they have an elongated body, a pointed head and a high, curved dorsal fin. The upper body is dark grey, with a softer, lighter pattern on the flanks, which fades to white on the belly and underside of the flippers. Very distinguishable from other species due to the diagonal white band on the upper side of the flippers.
Distribution and habitat use: Cosmopolitan distribution, present in the North Hemisphere from tropical waters to polar waters. They prefer areas along the continental slope, but can also occur in deeper waters. It is a resident species in Portugal, found all year round in Sagres.
Group size: Mainly solitary animals, sometimes in twos or threes, but larger groups can be seen in good feeding areas. Group composition is complex, with evidence for some segregation by age, sex and/or reproductive class.
Life span: Up to 50 years.
Gestation period: ca. 11 months. Calves are born with ca. 2-5m long and they reach maturity at 6-8 years. Births take place from December till March. Juveniles are weaned after 6 months.
Diet and Feeding: Wide variety of schooling fish and krill. In Portugal mainly feeds on small pelagic fish, horse mackerel and sardines. Feeds by engulfing or lunge-feeding. They can dive up to ca. 400 m and hold their breath up to 20 min.
Typical Behaviour: Fast swimmer, capable of up to 40km/h in short-bursts. Can be elusive when feeding as they spend little time at surface, although can also be inquisitive and will occasionally approach boats. Sometimes they will spy-hop and breach, particularly during rough weather. They typically dive for 3-10min, arching the back and tailstock quite high, without showing the fluke. Very diffuse blow, not well seen.
Population: Minimum c. 200 000 mature individuals worldwide. In Portugal, up to 50nm, the estimates of abundance at the end of the summer were 1406 individuals between 2010 and 2015. Population trend is stable.
Threats: Frequently involved in accidents with fishing activities, with bycatch being registered. Collisions with boats and anthropogenic noise are also threat factors.
IUCN status: Least concern for overall species worldwide (2018). In Portugal is Vulnerable (2023).
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Ferreira, M., Eira, C., López, A., & Sequeira, M. (2023). Balaenoptera acutorostrata baleia-anã. 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.
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