Perceived Temporal Shifts in Mediterranean Chondrichthyans: Insights from Fishers’ Ecological Knowledge in Italian Waters

Chondrichthyans are among the most threatened vertebrate groups worldwide, yet their ecology and long-term trajectories remain poorly understood in data-limited regions such as the Mediterranean Sea. This study used Local Ecological Knowledge (LEK) provided by fishers to investigate perception-based temporal changes in the reported composition of chondrichthyan taxa across Italian waters. A total of 57 semi-structured interviews were conducted across multiple Geographical Sub-Areas, collecting information on reported taxon occurrence, perceived abundance trends, and temporal contrasts between earlier and more recent phases of fishers’ careers. Overall, 35 taxa were reported. The number of taxa reported was significantly higher for the present than for the past. Rather than indicating a real increase in biodiversity, this pattern is more plausibly interpreted as a shift in ecological perception, potentially influenced by shifting baselines, changes in detectability, evolving fishing practices, and improved taxonomic awareness. Taxon-level analyses showed contrasting patterns, with some taxa increasing in reporting frequency, whereas others, such as Squatina squatina, declined markedly in contemporary reports. Anecdotal recollections of large catches and large individuals were consistent with fishers’ perceptions of historically more frequent encounters and body sizes, although these accounts should be interpreted as qualitative evidence. Several frequently reported taxa are currently classified as threatened, highlighting a mismatch between perceived commonness and conservation status. These findings show that LEK primarily reflects ecological perception and memory and should therefore be integrated with conventional data sources to support chondrichthyan conservation in the Mediterranean Sea.