Expedition report: Photo-identification and surveys of cetaceans in the central group of the Azores islands (March/April 2023)

• Main Authors: Steiner, Lisa, Machete, Miguel, Hammer, Matthias
• Format: Report
• Language: English
• Published: Zenodo 2024
• Subjects: baleen whale; baleen whales; Blue whale; Fin whale; Humpback Whale; Iceland; North Atlantic; Sei Whale; Sperm whale
• Online Access: https://doi.org/10.5281/zenodo.10775901

ABSTRACT In 2023 Biosphere Expeditions concluded its 17th year of cetacean photo-identification and distribution studies in the Azores. The expedition was based in Horta on the island of Faial and work was conducted around the three islands of Faial, Pico and São Jorge. The expedition ran from 20 March to 20 April 2023. 172 sightings of ten different species of cetacean and eight loggerhead turtles were recorded during the expedition period. Baleen whale photo-ID Blue Whale: The expedition recorded six blue whales in four encounters. Photos of individuals were shared with catalogues in Spain, Iceland and Canada. One blue whale matched to Pico, 2009, another to Pico, 2008. There were no international matches. Matches were made by Richard Sears of Mingan Island Cetacean Society. Fin whale: Three fin whales were recorded in two encounters. Identification photos were shared with catalogues in Spain, Iceland & Canada. No matches were found. Sei whale: Fourteen sei whales were recorded in eight encounters. There is no coordinated sei whale catalogue to share ID photos with, so photos were shared with sei whale researchers. Humpback whale: Three humpback whales were recorded during the expedition in seven encounters. One whale was seen four times on three different days. Another whale was seen twice on the same day. No international matches were found. The North Atlantic Humpback Whale Catalogue currently holds over 11,000 individuals and plays an important role in discovering long-range matches. Since 2004 the expedition has contributed 28 ID photos, helping to elucidate movements of the eastern Atlantic humpback whales, about which little is known. Summary: While still not as abundant as in previous years (2014-2017), more baleen whales were seen during the 2023 expedition than in 2022. There were further blue, fin, sei and humpback whales seen after the expedition. It is thought that this is connected to chlorophyll density in the water and therefore food availability. Sperm whale photo-ID Sperm whales were seen ...