Preliminary findings on the mass strandings of melon-headed whale Peponocephala electra on Boavista Island in November 2007, with notes on other cetaceans from the Cape Verde Islands
Van Waerebeek, K.; Hazevoet, C.J.; López Suárez, P.; Delgado Rodrigues, M.S.; Gatt, G. (2008). Preliminary findings on the mass strandings of melon-headed whale Peponocephala electra on Boavista Island in November 2007, with notes on other cetaceans from the Cape Verde Islands. Fondation Internationale du Banc d'Arguin: [s.l.]. 9 pp.
On 17-19 November 2007, two mass stranding events of melon-headed whales Peponocephala electra occurred in western Boavista, Cape Verde Islands, concerning 265 and 70 animals respectively. Only ca. 65 individuals could be successfully returned to the sea. Dead animals were immediately buried in a mass grave on the beach which however impeded necropsies and sampling. A study visit from 9-17 January 2008 attempted to reconstruct events, collect biological data and liaise with local stakeholders for improved documenting of future stranding events. Despite advanced decomposition, 16 specimens were exhumed. Samples collected include: skulls (n=9), stomach contents (n=3) and tissue samples (n=12). Screening of photographic evidence showed tightly grouped live-strandings, with many refloated individuals beaching again. The live-strandings and the total absence of tell-tale injuries associated with fishing gear excluded fisheries interactions. Good body conditions and indications of antemortem feeding were also inconsistent with epizootic infectious disease. Finally, nothing suggests that biotoxins or chemical contamination were involved, and the cause of the strandings remains unknown. The presence of submarine USS Annapolis in Cape Verde waters, apparently coinciding temporally with the strandings, led some to raise questions about the use of active sonar. Once identified, abundant squid beaks and fish otoliths found in fore- and main stomachs will provide valuable data on the feeding ecology of melon-headed whales in the eastern Atlantic. Study of cranial and genetic variation will help delineate population structure. A cursory examination of skeletal material of other small cetaceans, including pilot whales, did not support the occurrence of long-finned pilot whale G. melas in Cape Verde.
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