First representation of the trophic structure and functioning of the Portuguese continental shelf ecosystem: insights into the role of sardine

Detecting Regime Shifts in the Portuguese Continental Shelf Ecosystem Within the Last Three Decades

“…When building and calibrating the EwE model for the PCSE, we considered the best practice guide , reported uncertainties and thoroughly discussed limitations (Szalaj et al, 2021). Moreover, the model was well fitted to most groups with observation data, and we have confidence in the model and data it provided (Veiga- Malta et al, 2019;Szalaj et al, 2021). This was also reflected in this study because the results obtained from the analyses performed on observed biomass are in line with the results obtained from modelled biomass.…”

“…Fishing mortality and observed biomass data used in this study were also used as inputs of the EwE model, describing the PCSE between 1986 and 2017. The static version of this model was developed by Veiga- Malta et al (2019) and further updated and fitted to 32 years of time-series data by Szalaj et al (2021). Moreover, modelled biomass and ecosystem indicators data used in the study come as an output of this EwE model.…”

“…Indeed, the effects of the changes in dominant SPF on the ecosystem food web in the upwelling systems, have been broadly discussed (Cury et al, 2000). Moreover, based on the Ecopath model and description of the Iberian shelf food web structure, it has been demonstrated that sardine played an important role in the Iberian ecosystem, being an important key linkage between primary producers and top predators (Veiga- Malta et al, 2019). Moreover, the ecosim simulations demonstrated that sardine has an important role in a wasp-waist scenario (Szalaj et al, 2021).…”

“…Moreover, in the last decades, an increase in higher TL species has been documented (Leitão, 2015a). The causes underlying changes in the pelagic community are not clear but it has been suggested that they result from a complex interplay between environmental variability, species interactions and fishing pressure (Leitão et al, 2014a;Leitão, 2015b;Veiga-Malta et al, 2019). There is evidence, that changes in the intensity of the Iberian coastal upwelling (resulting from the strengthening or weakening northern winds) had occurred in the last decades.…”

Interactions between the common dolphin, Delphinus delphis, and the Portuguese purse seine fishery over a period of 15 years (2003–2018)

“…The north‐west coast is characterized by a wider (40–70 km) and flatter continental shelf than the south‐west (10–20 km) and south (5–20 km) coasts and is also under the influence of a strong upwelling. Thus, being an area of high productivity (Fiúza, Macedo & Guerreiro, 1982; Fiúza, 1983), the north‐west coast is suitable for small pelagic fish species and is therefore attractive to a large number of cetacean species (Zwolinski et al, 2010; Veiga‐Malta et al, 2019). It is the area in Portuguese waters with the greatest abundance of sardine, the preferred prey of the common dolphin, and is the main nursery and recruitment area of this pelagic fish, centred off Aveiro‐Figueira da Foz (40°–41°N) (Silva et al, 2009; Rodríguez‐Climent et al, 2017).…”