Percorrer por autor "Monteiro, Silvia S."
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- Foraging ecology and fisheries interactions of common bottlenose dolphins (Tursiops truncatus) inferred from strandings in western iberian atlantic watersPublication . Marçalo, Ana; Nicolau, Lídia; Torres‐Pereira, Andreia; Eira, Catarina; Araújo, Helder; Oliveira, Isabel; Santos, Jorge; Casero, Maria; Ferreira, Marisa; Sequeira, Marina; Sá, Sara; Monteiro, Silvia S.; Vingada, José; Giménez, JoanThe common bottlenose dolphin (Tursiops truncatus) is a resident species along the Portuguese mainland coast, yet knowledge of its stranding patterns and feeding ecology is scarce. This study presents a comprehensive assessment of strandings (n=264, from 1980 to 2019) and feeding ecology based on stomach content analysis (n=43 from 1997 to 2019) along the Portuguese mainland coast. Strandings were more frequent in the first half of the year and have increased in recent decades, particularly along the northwestern and southern coasts, likely reflecting improved monitoring efforts. Dietary analysis revealed a predominantly piscivorous diet (>85% by number and weight), with prey including pelagic, meso-pelagic, and demersal fish species. Hake (Merluccius merluccius), conger eel (Conger conger), and blue whiting (Micromesistius poutassou) emerged as the most important prey items. Despite a preference for demersal and mesopelagic fish, dolphins exhibited dietary plasticity, foraging across diverse habitats, likely adapting to local prey availability. The substantial dietary overlap with commercially targeted species, particularly by small-scale and coastal fisheries, suggests potential interactions and competition for shared resources. These findings provide valuable insights into the trophic ecological role of bottlenose dolphins in the region and highlight the need to consider this species in ecosystem-based fisheries management and conservation planning.
- Portuguese purse seine fishery spatial and resource overlap with top predatorsPublication . Wise, Laura; Galego, Catarina; Katara, Isidora; Marçalo, Ana; Meirinho, Ana; Monteiro, Silvia S.; Oliveira, Nuno; Santos, Jorge; Rodrigues, Pedro; Araujo, Helder; Vingada, Jose; Silva, AlexandraThe Portuguese purse seine fishery, with average annual catches of 70 000 tonnes, operates mainly in coastal areas and targets small pelagic fish (SPF). Potential competition for resources may occur between the fishery and some species of marine mammals and seabirds, as suggested by observed incidental catches. For those species directly affected by the fishery, the spatial distribution of marine taxa and the fishing fleet are key pieces of information for spatial planning and management. We analysed the spatial and resource overlap between the fishery's distribution and effort, and the distribution and abundance of 6 species of top predators -seabirds (n = 4) and marine mammals (n = 2) between 2010 and 2014. Estimates of annual consumption by top predators and the fishery catch within the distributional range of one of their main prey species (sardine Sardina pilchardus) were also determined. Spatial overlap between all considered species and the fishery was low (<0.221), and only 2 species (common dolphins Delphinus delphis and Cory's shearwaters Calonectris borealis) showed high resource overlap with the fishery (>0.7). Overall, values of consumption of SPF by the top predators were of the same order of magnitude as mean annual purse seine landings for the studied area. Our results can be used for marine spatial planning, including designation of Marine Protected Areas and the development of an ecosystem-based model for the effective management of the Portuguese purse seine fishery that takes into account the consumption of natural predators.