Age validation of the European Anchovy (Engraulis encrasicolus Linnaeus, 1758) in the Central-Southern Tyrrhenian Sea (West Mediterranean Sea)

The validation of growth of the European Anchovy (Engraulis encrasicolus Linnaeus, 1758) presents several gaps in the Mediterranean Sea, despite its growth has been widely studied using different methods. The uncertainty in estimating the European Anchovy age by otolith interpretation is linked to (i) the identification of the first growth ring; (ii) the presence of false increments; (iii) discrepancies in the applied age scheme (e.g. theoretical birthdate); and (iv) the progressive compactness of the last annuli in older specimens. The present study was conducted on specimens caught in Central-southern Tyrrhenian Sea between 2012 and 2016. The analyses of the otolith edge type and the marginal increment analysis allowed to describe the annuli deposition pattern, with the opaque ring deposited from June to September, and the translucent ring from October to May. The growth pattern inferred from the European Anchovy otoliths was either corroborated or indirectly validated by the agreement between the length–frequency results and the otolith age estimation. No significant differences were found between the von Bertalanffy growth curves calculated by otolith interpretation (back-calculation and direct otolith reading) and the LFDA. These outcomes resulted highly relevant for species, such as small pelagic fish, for which the direct validation methods (e.g. mark-recapture, captivity, radiochemical) are particularly difficult to implement.