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Projeto de investigação
INFLUÊNCIA DE FACTORES ANTROPOGÉNICOS NA COMUNIDADE DE PEQUENOS CETÁCEOS AO LONGO DA ZONA COSTEIRA DO CENTRO DE PORTUGAL
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Assessment of harbour porpoise bycatch along the Portuguese and Galician Coast: insights from strandings over two decades
Publication . 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, Catarina
The 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 waters
Publication . 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, Joan
The 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.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
FARH
Número da atribuição
SFRH/BD/30240/2006