Browsing by Author "Fortuna, Caterina"
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- Population structure of short-finned pilot whales in the oceanic archipelago of Madeira based on photo-identification and genetic analyses: implications for conservationPublication . Alves, Filipe; Quérouil, Sophie; Dinis, Ana; Nicolau, Cátia; Ribeiro, Cláudia; Freitas, Luís; Kaufmann, Manfred; Fortuna, Caterina1. Pilot whales Globicephala spp. are known to display a hierarchical social pattern, but longitudinal data to infer population structure of short-finned pilot whales Globicephala macrorhynchus are rare. 2. Using data collected between 2003-2011 in the oceanic archipelago of Madeira, the grouping structure of short-finned pilot whales was studied using photo-identification methods and mtDNA sequences and microsatellite markers to test the hypotheses that (1) there is at least one pelagic and one or more island-associated communities, and (2) groups are made of related individuals, with a matrilineal social structure. 3. Pilot whales demonstrated a large degree of variability in site fidelity, including residents (up to 14-year interval), regular visitors and transients. The social and temporal analyses revealed a well-differentiated society with long-lasting relationships (of years). The genetic analyses suggested that individuals of the three residency patterns may not be genetically isolated, and that small groups are made up of related individuals, suggesting some degree of social philopatry, while large groups are probably temporary associations of smaller groups. 4. It is proposed that the pilot whales encountered in Madeira belong to a single population encompassing several clans, possibly three clans of island-associated whales and others of transients, each containing two to three matrilineal pods, each with a mean of 15 individuals (SD=9, range: 4-29). We suggest that the clans interact for mating purposes when they meet. 5. For management decisions, it is considered that the island-associated whales should not be regarded as demographically independent populations, but instead as stable social entities to be included in governmental management plans and requiring periodic evaluation of their status. The high proportion of marked individuals and low rate of mark change encourages further research in this species.
- Survival and abundance of short-finned pilot whales in the archipelago of Madeira, NE AtlanticPublication . Alves, Filipe; Dinis, Ana; Nicolau, Cátia; Ribeiro, Cláudia; Kaufmann, Manfred; Fortuna, Caterina; Freitas, LuísEstimates of population parameters for the short-finned pilot whale, Globicephala macrorhynchus, are scarce in literature, contributing to an International Union for Conservation of Nature (IUCN) status of Data Deficient. In this study, photo-identi fication data collected over 7 yr from Madeira were used to estimate for the first time survivorship, capture probability, and abundance in this species using mark-recap ture methodology. The Cormack-Jolly-Seber model estimated that the adult island associated (i.e., resident and regular visitor) whales had a constant survival rate of 0.960 (95% CI: 0.853–0.990) and an annual capture probability varying between 0.372 (CI: 0.178–0.619) and 0.843 (CI: 0.619–0.947). A parameterization of the Jolly-Seber model estimated that 140 island-associated whales (CI: 131–151) used the area throughout the course of the study. Based on a closed population model, the most precise (lower CV) annual estimate of the total number of pilot whales using the southern and eastern waters of Madeira (~900 km2 ) in a 3 mo period covering summer/autumn was 334 animals (CI: 260–437). No trend was observed. Despite including biases, the approach used in this study provided plausible estimates of population parameters, which can contribute to the regional conservation strategies.