Publicação
Behavioural ecology and habitat use of bottlenose dolphin (Tursiops truncatus) in São Tomé and Príncipe
| Resumo: | Ecological factors related to habitat type that influence food resources are major determinants in the way animals occur, select habitats, behave and interact with each other. The bottlenose dolphin is a cosmopolitan species, and because of its coastal habits in some areas populations have been declining. Additionally, in open environments there is a gap regarding information and assessment of this species. Although the ocean around São Tomé and Príncipe is relatively undisturbed, human activities such as artisanal fisheries, may affect directly cetaceans. Whale watching and oil exploration are factors that are beginning to emerge in the region and are also relevant for cetaceans. The aim of this thesis was to study the behavioural ecology of bottlenose dolphin through distribution, abundance, social structure, behaviour and group characteristics, residency patterns and site fidelity. Sighting effort from boat-based surveys was conducted between 2002-2006 and in 2012 around São Tomé Island and subsequently photo-identification techniques were used A total of 140 individuals were photo-identified and data suggested the existence of an open population of about 214 individuals. Group size had a mean of 44.7 individuals and it seemed to be influenced by habitat characteristics and composition. Key areas for bottlenose dolphin in São Tomé Island were determined using maximum entropy modelling. The most important environmental variables influencing distribution were distance to the coast and to river mouths, depth and seabed aspect. The eastern coast of São Tomé and Rolas islet presented the most suitable areas but they overlapped with intense fishing areas. Consequently, negative interactions between humans and cetaceans may occur through by-catch, direct hunting and competition. The assessment of key areas for bottlenose dolphins and the study of behaviour and abundance will contribute towards to the implementation of adequate conservation efforts for São Tomé and Príncipe from which all marine biodiversity would benefit. |
|---|---|
| Autores principais: | Pereira, Andreia Filipa da Silva, 1985- |
| Assunto: | Mamíferos aquáticos Comportamento animal Golfinhos Tursiops truncatus São Tomé e Príncipe Teses de mestrado - 2012 |
| Ano: | 2012 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Ecological factors related to habitat type that influence food resources are major determinants in the way animals occur, select habitats, behave and interact with each other. The bottlenose dolphin is a cosmopolitan species, and because of its coastal habits in some areas populations have been declining. Additionally, in open environments there is a gap regarding information and assessment of this species. Although the ocean around São Tomé and Príncipe is relatively undisturbed, human activities such as artisanal fisheries, may affect directly cetaceans. Whale watching and oil exploration are factors that are beginning to emerge in the region and are also relevant for cetaceans. The aim of this thesis was to study the behavioural ecology of bottlenose dolphin through distribution, abundance, social structure, behaviour and group characteristics, residency patterns and site fidelity. Sighting effort from boat-based surveys was conducted between 2002-2006 and in 2012 around São Tomé Island and subsequently photo-identification techniques were used A total of 140 individuals were photo-identified and data suggested the existence of an open population of about 214 individuals. Group size had a mean of 44.7 individuals and it seemed to be influenced by habitat characteristics and composition. Key areas for bottlenose dolphin in São Tomé Island were determined using maximum entropy modelling. The most important environmental variables influencing distribution were distance to the coast and to river mouths, depth and seabed aspect. The eastern coast of São Tomé and Rolas islet presented the most suitable areas but they overlapped with intense fishing areas. Consequently, negative interactions between humans and cetaceans may occur through by-catch, direct hunting and competition. The assessment of key areas for bottlenose dolphins and the study of behaviour and abundance will contribute towards to the implementation of adequate conservation efforts for São Tomé and Príncipe from which all marine biodiversity would benefit. |
|---|