Typologies and occurrences of skeletal anomalies observed all along the productive chain of gilthead seabream Sparus aurata aquaculture

The presence of skeletal anomalies in fishes is a by-product of aquaculture and it entails economic, biological and ethical issues. Gilthead seabream and European seabass, Dicentrarchus labrax, have been the first valuable euryhaline species to be reproduced in controlled condition and intensively reared in Mediterranean aquaculture since the 1980s. Nonetheless, detailed information on skeletal anomalies occurrences and typologies all along the productive chain is still lacking in literature. This knowledge could furnish data on trend of skeletal anomalies occurrences and typologies in the different rearing phases, in spite of selections carried out during the productive chain, and information on anomalies in ontogenetic, modeling and remodeling processes of skeletal elements. The final goal is the optimization of rearing conditions for improving Mediterranean aquaculture profits and welfare of reared gilthead seabream. Seabream were sampled from hatchery, ongrowing and commercial size lots from intensive commercial farms. Commercial size seabream were sampled from both off-shore and land-based farms. As many as 874 reared seabream were analyzed for skeletal anomalies and variation in meristic counts and obtained data compared with same-size wild seabream lots. The reared and wild seabream specimens resulted well differentiate onto the basis of the anomalies pattern, with reared lots resulting always more and highly deformed than the wild ones. Some variability in meristic counts was observed also in wild lots, except for pectoral fin radials. The most variable character was the number of caudal rays, both in reared and in wild lots. Some anomalies were present only in some farm. The pre-ongrowing lots showed the highest percentages of anomalous individuals. The number of anomaly typologies augmented with the size of the individuals, conversely to the frequency of severe anomalous individuals which lowered with size. The average number of anomalies for affected seabream was found higher in commercial size lots, and similar in pre-ongrowing and hatchery lots. Severe anomalies mainly affected ongrowing lots with a charge quite similar in all the lots. This study was funded by the Italian Ministry for Agriculture, Food and Forestry Policy (Law 41/82)