Small pelagic fish fitness relates to local environmental conditions and trophic variables

Small pelagic fish (SPF) are key organisms for the functioning of marine ecosystems. In recent decades, these species have undergone significant changes in biomass, growth and body condition Mediterranean Sea. Seasonal spatial information about biological ecological traits SPF their relationship with environmental variables is still missing. Here, we investigated along a latitudinal gradient Northwestern Sea seasonal patterns fitness (in terms condition, fat content reproduction activity) two important SPF, European anchovy (Engraulis encrasicolus) sardine (Sardina pilchardus). We used non-parametric multivariate analyses Generalized Additive Models (GAMs) to investigate which trophic could explain observed variations during 2018–2019. Mean values, relative index (Kn) gonadosomatic (GSI) were calculated monthly. also measured individual’s stable isotope composition muscle. Chlorophyll-a, sea surface temperature salinity as descriptors. The results revealed temporal both indices, well isotopic values. GAMs showed that variability was mostly explained by variables, addition factors. Trophic contributed case anchovy. This study provides insights into interplay commercial gradient, contributes understand fluctuations population declining trends inform proactive fisheries management at local regional scale.