Animal-based measures for operational welfare indicators at wholesale level in gilthead seabream (Sparus aurata) reared in the Mediterranean Sea

The study evaluated animal-based welfare indicators in gilthead seabream (Sparus aurata) from different Mediterranean suppliers across two harvest seasons. Indicators included fish biometry, condition indexes, morphological anomalies, and caudal fin erosion. A total of 540 seabream (367 ± 46 g) from 18 lots (30 fish/lot) were obtained from three supplier origins (Croatia, Greece, Turkey; 6 lots each) and two seasons (autumn and spring; 9 lots each). Seabream from Turkey were smaller (−4 % length, −5 % weight; P < 0.001), had higher perivisceral fat (1.49 % vs. 0.67 %; P < 0.001), and a higher condition factor (+6 %; P < 0.001) compared to Croatia and Greece. Autumn-harvested fish were heavier (+9 % weight; P < 0.001), had a higher condition factor (+10 %; P < 0.001), and fillet yield (+4.9 %; P < 0.001) compared to spring. Vertebral column anomalies averaged 3.0 %, but three lots showed high incidences (16.7 %, 20.0 %, 16.7 %), with significant effects of supplier origin (P < 0.001) and season (P < 0.01). Skull anomalies (5.4 %) were found in 15 out of 18 lots, significantly differing by supplier origin (P < 0.001). Eye anomalies averaged 0.7 % with no seasonal or supplier effect. Caudal fin erosion occurred in 77 % of fish (range: 33–100 %), with an average erosion index (FEI) of 0.72. Fish from Greece exhibited the highest occurrence (88 %) and severity (FEI = 0.92), while autumn-harvested fish had higher erosion (FEI: 0.75 vs. 0.65; P < 0.001). This study provides a first characterization of seabream welfare indicators at market level, revealing significant variability influenced by supplier origin and harvest season. These findings could inform thresholds for on-farm welfare monitoring and support welfare labelling of Mediterranean cage-farmed fish under commercial conditions.