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The abundance of humpback whales occurring around Boa Vista, Cape Verde Islands, was estimated by markrecapture modelling. Photographs of markings on tail flukes of individual whales were collected during the breeding season. Sighting histories were constructed for each individual and an abundance of 171 animals was estimated using a Jolly-Seber mark-recapture model. Correcting for known biases arising due to sex-specific behaviour and temporary emigration insofar as possible, an estimate of 260 whales was obtained. This is significantly higher than the previous estimate of 99 humpback whales from this region. Due to limited survey effort it is not known how representative the study area is of the entire Cape Verde archipelago and this estimate may be considered to be biased low and serves as a minimum estimate. The high recapture probability (0.37) coupled with the low abundance is consistent with a small local population. The low survival rate (0.86) suggests possible emigration and further studies are needed to assess connectivity between humpback whales breeding in Cape Verde and other breeding locations. The amount of exchange between groups of whales breeding in Cape Verde and adjacent areas remains unknown. It is unclear whether the abundance estimate herein applies to part of an isolated population or part of a larger and continuous one.
During August-September 2014 and 2015, yachtbased surveys were conducted in the Cape Verde archipelago with the main objective of trying to locate humpback whales Megaptera novaeangliae during the late boreal summer (Berrow et al. 2014). Spring breeding humpbacks in Cape Verde waters are known to have their feeding grounds in the high Arctic (e.g. Wenzel et al. 2009). While these animals have generally left the breeding grounds by mid-May, a number of sightings during the summer months (June- August) have raised the possibility that animals from southern stocks may occasionally reach as far north as Cape Verde (Hazevoet et al. 2011).
First record of a live false killer whale Pseudorca crassidens (Owen, 1846) in Cabo Verdean waters
(2017)
Despite the limited research on cetaceans in Cabo Verde waters, 23 species have been documented (Hazevoet & Wenzel 2000, Hazevoet et al. 2010, Koenen et al. 2013, Berrow et al. 2015). The presence of several species is known only from strandings, such as the false killer whale, which has beached dead twice on Boavista in the 1980s–1990s, and again in 2007 (Hazevoet et al. 2010, Koenen et al. 2013). This is a CITES species, and Data Deficient according to IUCN (Taylor et al. 2008).