Percorrer por autor "Eira, Catarina"
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- Assessment of harbour porpoise bycatch along the Portuguese and Galician Coast: insights from strandings over two decadesPublication . Torres-Pereira, Andreia; Araújo, Hélder; Monteiro, Silvia Silva; Ferreira, Marisa; Bastos-Santos, Jorge; Sá, Sara; Nicolau, Lídia; Marçalo, Ana; Marques, Carina; Tavares, Ana Sofia; De Bonis, Myriam; Covelo, Pablo; Martínez-Cedeira, José; López, Alfredo; Sequeira, Marina; Vingada, José; Eira, CatarinaThe Iberian harbour porpoise population is small and fisheries bycatch has been described as one of its most important threats. Data on harbour porpoise strandings collected by the Portuguese and Galician stranding networks between 2000 and 2020 are indicative of a recent mortality increase in the western Iberian coast (particularly in northern Portugal). Overall, in Portugal and Galicia, individuals stranded due to confirmed fishery interaction represented 46.98% of all analysed porpoises, and individuals stranded due to probable fishery interaction represented another 10.99% of all analysed porpoises. Considering the Portuguese annual abundance estimates available between 2011 and 2015, it was possible to calculate that an annual average of 207 individuals was removed from the population in Portuguese waters alone, which largely surpasses the potential biological removal (PBR) estimates (22 porpoises, CI: 12–43) for the same period. These results are conservative and bycatch values from strandings are likely underestimated. A structured action plan accounting for new activities at sea is needed to limit the Iberian porpoise population decline. Meanwhile, there is an urgent need for a fishing effort reorganization to directly decrease porpoise mortality.
- 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.
- Stranding patterns and feeding ecology of striped dolphins, Stenella coeruleoalba, in Western Iberia (1981–2014)Publication . Marçalo, Ana; Giménez, Joan; Nicolau, Lídia; Frois, Jessica; Ferreira, Marisa; Sequeira, Marina; Eira, Catarina; Pierce, Graham J.; Vingada, JoséThe striped dolphin, Stenella coeruleoalba, is one of the most abundant cetacean species off the Western Iberian coast, however, studies on the species regarding biology, ecology, threats or conservation efforts are lacking. This study investigates stranding patterns (years 1981–2014) and diet (2002–2014) of striped dolphins (Stenella coeruleoalba) off the Portuguese mainland coast. Stranded animals were sampled along the whole coast (n = 252). Most stranded striped dolphins were recorded in the first half of the year and strandings increased over time. Analysis of stomach contents (n = 36) showed that striped dolphins in the area are mostly piscivorous (80% by number and weight of the diet), taking pelagic, meso-pelagic and demersal species. In terms of reconstructed biomass prey, sardine (Sardina pilchardus) and blue whiting (Micromesistius poutassou) were the most important. Prey items revealed that both sexes forage at a range of depths (pelagic and demersal systems) in both neritic and oceanic habitats, although females feed more often in coastal waters. Moreover, diet results also indicate that striped dolphins may co-occur with other neritic cetacean species, such as the common dolphin, Delphinus delphis, thus sharing some preferred prey species. The study revealed that striped dolphins on the Iberian coast interact with coastal fisheries sharing the same target species. Management measures for fisheries will need to be consistent with an ecosystem-based approach.