Recruitment of Anchovy and Sardine in the Adriatic Sea and Environmental Factors

Anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) are important fishery resources in the Adriatic Sea. Since 1975, CNR-ISMAR-Ancona has been conducting research on these stocks in the central and northern Adriatic Sea, particularly on their dynamic. The level of recruitment to the stock has been estimated by means of population dynamics methods for both species and was analyzed to identify possible effects related to changes in some environmental variables, in particular Po River flow rate, wind stress and North Atlantic Oscillation (NAO) index. At this aim, different types of regression models were applied. A positive correlation was found between anchovy recruitment and Po River flow rate and quadrant specific wind stress. On the other hand, the influence of Po River seemed to be weaker for sardine, while a positive correlation between NAO index and recruitment was found for this species. Moreover, about the role of Po River runoff on anchovy, useful elements were also obtained from some investigations on the growth pattern of young stages preceding recruitment. Further investigations in both stock assessment and biology could provide a better understanding of the influence of environment on the recruitment of Adriatic anchovy and sardine, allowing also an improvement in stock management, e.g. forecasts.