Assessing cetacean occurrence along a fixed transect in the Madeira archipelago

• Main Author: Carvalho, Patrícia Pereira de Gouveia Ferreira de
• Other Authors: Santos, Manuel Eduardo dos
• Format: Master Thesis
• Language: English
• Published: 2020
• Subjects: Cetaceans; Spatio-temporal occurrence; Platforms of opportunity; Madeira archipelago; Cetáceos; Ocorrência espaço-temporal; Plataformas de oportunidade; Arquipélago da Madeira; Domínio/Área Científica::Ciências Naturais::Ciências Biológicas; Santo Island; Physeter macrocephalus; Sperm whale
• Online Access: http://hdl.handle.net/10400.12/7632

Dissertação de Mestrado apresentada no ISPA – Instituto Universitário para obtenção de grau de Mestre na especialidade de Biologia marinha e conservação. Cetaceans are key species in marine ecosystems, knowledge of their distribution patterns is fundamental not only for their conservation and management, but also for their habitat. Still, data on their occurrence in Madeira Archipelago, is fragmented and scarce. For the current study, platforms of opportunity were used to collect data, resulting in 17,000 km surveyed, 590 sightings and the identification of eleven species, from a two-year sampling range between June 2016 and June 2018. The current study also gives new insights into unexplored or under- studied areas, such as the area between Madeira Island and Porto Santo Island. From all the identified species, only those with a number of sightings equal or greater than 20 were included to determine encounter rates and investigate temporal and spatial distribution, these were, Atlantic spotted dolphin (Stenella frontalis), common bottlenose dolphin (Tursiops truncatus), short-beaked common dolphin (Delphinus delphis), short-finned pilot whale (Globicephala macrorhynchus), sperm whale (Physeter macrocephalus) and Bryde’s whale (Balaenoptera edeni). Correlation between spatial distribution and environmental habitat variables, such as distance to coast and depth, was also inferred. Hence this thesis aims to contribute to increase the enrichment of knowledge regarding cetacean presence in the Madeira archipelago by looking into their spatio-temporal patterns of distribution. Results have pinpointed the richness of the studied area, as cetaceans occurred through the entire route, with the identification of a total of 11 from the 29 species identified for the Madeira archipelago. The correlation between distance to coast and depth seems to influence the distribution of some species. Among the sighted species, the Bryde’s whale showed a preference for coastal waters, while the sperm whale seems to occur most ...