Percorrer por autor "Santos, Paulo T."
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- Further improvements in sorting grids for the crustacean trawl fishery off the Southern coast of PortugalPublication . Millar, Russell B.; Barros, Luisa; Fonseca, Paulo; Santos, Paulo T.; Campos, AidaBottom-trawl fishing for crustaceans off the Portuguese south and southwest coasts is a very important segment of the Portuguese fishing fleet, where annual rates of discarding have ranged from approximately 38% to as much as 70% of the total catch. Past experiments to address this problem encompassed the testing of different codend mesh sizes and configurations, square mesh windows and rigid grids to enhance species and size-selectivity. While the use of a Nordmore grid has proved quite efficient in separating out blue whiting (Micromesistius poutassou), it also led to some losses of the two main crustacean target species, Norway lobster (Nephrops norvegicus) and rose shrimp (Parapenaeus longirostris). The present study addresses that limitation by using a modified grid with 20 mm bar spacing and two open sections, designed with the purpose of separating fish and crustacean species into upper and lower codends. Good separation was achieved, with about 80% of the blue whiting (in number) directed towards the upper trawl section and caught in the upper codend, while a similar percentage of Norway lobster was caught in the lower codend. The grid bars had 50% retention for Norway lobster at 34.1 mm carapace length. The results herein will enable this gear configuration to be finetuned with regard to codend mesh sizes and bar spacing, so as to optimize both retention of Norway lobster and exclusion of blue whiting. For example, compared to using the minimum 70 mm diamond mesh size, using an 80 nun diamond mesh upper codend would reduce Norway lobster catch weight by just 1.6% but reduce the number of blue whiting caught by 42%.
- Inversions dominate evolution in the european sardine (sardina pilchardus) amid strong gene flowPublication . Sabatino, Stephen J.; Cabezas, M. Pilar; Pereira, Paulo; Garrido, Susana; Santos, António M.; Carneiro, Miguel; Santos, Paulo T.; Louro, Bruno; Cox, Cymon; Canario, Adelino; Veríssimo, AnaInversions can play key roles in the genetic architecture of adaptation, but the scale of their effects across different species remains poorly understood. Here, we use whole-genome sequencing and demographic modelling to investigate the influence of inversions on the population genomics of the r-selected European sardine (Sardina pilchardus). Allele frequency differences from millions of SNPs across 34 populations spanning the species' range were analysed. Genomic scans identified several extreme outlier regions overlapping large inversions (29–52Mbp), collectively representing over half the genome. Our findings suggest these inversions correlate with locally adapted life-history strategies. First, SNPs within outlier regions containing inversions exhibited striking allele frequency differences between Atlantic and Mediterranean sardines, which differ in key adaptive life-history traits. In the Atlantic, inversion allele frequencies varied latitudinally, while in the Mediterranean, they shifted longitudinally, aligning with temperature and oceanographic features that influence sardine life-history strategies. Moreover, adjacent populations in contrasting environments exhibited pronounced differences in inversion allele frequencies, accompanied by a marked reduction in migration between them. In contrast, spatial patterns at neutral loci showed widespread gene flow, isolation by distance within basins, and population structure between Atlantic and Mediterranean basins (except for the Canary Islands). These results suggest that the inversions studied are under selection and demonstrate the capacity of large inversions to shape genomewide patterns of genetic diversity and population structure in species characterized by widespread gene flow. Our work also offers crucial insights for stock delimitation and management of this commercially valuable species in the face of climate change.