Comparing the trophic ecology of three sympatric Mediterranean skate species from a Fishery Exclusion Zone of the Central Mediterranean Sea

Elasmobranchs are experiencing an alarming decline within the Mediterranean basin driven by human activities. Among them, batoids represent important and widespread mesopredators within bentho-demersal food webs. Despite their ecological relevance, information on the feeding habits and trophic interactions among Mediterranean batoids species remain fragmentary and poor. Present research aims to investigate the trophic ecology of Raja clavata, Raja miraletus, and Raja montagui in a Fishery Exclusion Zone falling within the Southern Tyrrhenian Sea. It provides data on their diets also testing the null hypothesis of no differences in trophic niche at intra- and interspecific level by analyzing niche breadths and overlaps among maturity stages (immature vs mature individuals). Raja specimens were sampled during two scientific trawl survey's performed in Autumn-Winter (2023), including all the specimens (26 Raja clavata, 25 Raja miraletus and 31 Raja montagui) caught in 20 hauls from between 0 and 350 m of depth. Stomach content analysis was perfomed to reconstruct diet composition of the three studied species. The results showed a significant role of crustaceans in their diet during both the explored ontogenetic stages, with a highest Levins' index in R. miraletus (both in mature and immature specimens) and lowest in R. clavata. TROPH values were comparable, indicating that the three species belong to the same trophic level. Overlap in trophic niches, measured by the Morisita's index, was highest between R. montagui and R. clavata, whereas R. miraletus showed the most distinct niche, as also confirmed by the null model analysis. Results highlighted the role as mesopredators of Raja species in the Central Mediterranean Sea, suggesting a coexistence facilitated by prey selection that requires further investigations to be fully confirmed and described.