Variability in size at maturity of the European anchovy (Engraulis encrasicolus) in the Mediterranean Sea

Περίληψη

Size at first sexual maturity (L₅₀) represents an important life history trait in the development of management measures providing fundamental information to avoid the exploitation of younger individuals. L₅₀ is known to display variability due to fishing pressure, geographical gradient and environmental features. In this study, in order to investigate L₅₀ variability among areas of the Mediterranean and Black Sea, maturity ogives of anchovy (Engraulis encrasicolus) were estimated by considering samples collected during the anchovy spawning period in the framework of the MEDiterranean International Acoustic Survey (MEDIAS) program. Anchovy size and sexual maturity data from several Geographical Sub-Areas (GSA) – i.e. Northern Spain, Gulf of Lion, Tyrrhenian Sea, Strait of Sicily, Adriatic Sea and Black Sea – were gathered according to a standard methodological protocol. Maturity ogives were estimated by means of a logistic regression taking into account  total length, condition factor, sex and GSA. Obtained results evidenced a significant effect of condition factor, fish in better condition reaching maturity earlier, as well as differences in L₅₀ values among areas and between sexes, with males reaching the maturity at lower length than females. Even though the obtained L₅₀ estimates are relative to the spawning period only, the observed variability at the Mediterranean basin scale highlights the importance to explicitly consider the habitat peculiarities in order to provide management advices based on an ecosystem approach to fishery.