Sara Sá

Pygmy ( Kogia breviceps ) and dwarf ( Kogia sima ) sperm whales are among the least studied cetaceans due to their elusive behavior and low detectability at sea. Molecular approaches are therefore essential to clarify their taxonomy, population structure, and conservation status. We present new mitochondrial DNA data from stranded K. breviceps and K. sima specimens collected across the eastern North Atlantic, a region previously not represented in genetic studies. We analyzed fragments of the mitochondrial cytochrome b gene and control region from 56 individuals and integrated these data with publicly available sequences to place regional diversity within a global phylogeographic framework. Population genetics, phylogenetics, and haplotype network analyses showed a weak or absent population structure in K. breviceps across its range, whereas K. sima was consistently separated into Atlantic–Mediterranean and Indo‐Pacific lineages, characterized by high genetic divergence. Eastern North Atlantic samples clustered within the Atlantic lineage and showed moderate genetic diversity, with a few locality‐specific haplotypes identified. Overall, our results expand the genetic baseline for Kogiidae species in the eastern North Atlantic and support previous evidence of cryptic diversity within K. sima . Despite observational limitations, the relatively high genetic diversity observed in the two species provides cautiously optimistic indications of population health in this elusive cetacean family.

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.

This study characterises microplastics in small cetaceans on the coast of Portugal and assesses the relationship between several biological variables and the amount of detected microplastics. The intestines of 38 stranded dead cetaceans were processed in the laboratory, with digestion methods adapted to the amount of organic matter in each sample. The influence of several biological and health variables (e.g., species, sex, body condition) on the amount of microplastics was tested in all analysed species and particularly in common dolphins, due to the larger number of available samples. Most of the analysed individuals had microplastics in the intestine (92.11%), with harbour porpoises revealing a significantly higher median number of microplastics than common dolphins, probably due to their different diets, use of habitat and feeding strategies. None of the other tested variables significantly influenced the number of microplastics. Moreover, the microplastics found should not be enough to cause physical or chemical sublethal effects, although the correlation between microplastic ingestion and plastic additive bioaccumulation in cetacean tissues requires further investigation. Future monitoring in biota should rely on improved and standardised protocols for microplastic analyses in complex samples to allow for accurate analyses of larger samples and spatio-temporal comparisons.

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.

The Iberian porpoise population is small and under potentially unsustainable removal by fisheries bycatch. Recently, a marine Site of Community Importance (SCI) was legally approved in Portugal, but no measures ensued to promote porpoise conservation. Information about porpoise abundance and distribution is fundamental to guide any future conservation measures. Annual aerial surveys conducted between 2011 and 2015 show a low overall porpoise abundance and density (2254 individuals; 0.090 ind/km², CV = 21.99%) in the Portuguese coast. The highest annual porpoise estimates were registered in 2013 (3207 individuals, 0.128 ind/km²), followed by a sharp decrease in 2014 (1653 individuals, 0.066 ind/km²). The porpoise density and abundance estimated in 2015 remained lower than the 2013 estimates. A potential distribution analysis of the Iberian porpoise population was performed using ensembles of small models (ESMs) with MaxEnt and showed that the overall habitat suitability is particularly high in the Portuguese northern area. The analysis also suggested a different pattern in porpoise potential distribution across the study period. These results emphasize the importance of further porpoise population assessments to fully understand the spatial and temporal porpoise habitat use in the Iberian Peninsula as well as the urgent need for on-site threat mitigation measures.