Recruitment of Engraulis japonicus and its environmental drivers: An EDM analysis

Abstract

Anchovies are the key trophic links between secondary production and higher trophic levels, and their recruitment changes have the potential to cascade and affect higher trophic levels. Therefore, understanding the stock-recruitment relationships and the external drivers of recruitment has important ecological and fishery management implications. In this study, we employed empirical dynamic modelling (EDM) to analyze the recruitment dynamics of Japanese anchovy (Engraulis japonicus) in the Yellow Sea large marine ecosystem (YSLME), based on data from surveys of the YSLME. The results indicated that biological effects between the YSLME Japanese anchovy stock and its recruitment were deterministic and bidirectional (interplay of causality in both directions). Japanese anchovy recruitment was also driven by other external factors, chief among these was fishing pressure which plays a decisive role in overall recruitment of the YSLME. In contrast, climate related factors act more locally on recruitment. We conclude that the decline in Japanese anchovy biomass is mainly caused by overfishing. This has important implications for rebuilding and subsequent management of Japanese anchovy stock: under current climate pressure, the EDM showed that reducing fishing pressure would promote recovery of stock biomass and recruitment.