Importance of trophic mismatch in a winter-hatching species: evidence from lesser sandeel

Understanding the mechanisms responsible for variability in fish recruitment can improve our ability to predict the response of marine species to environmental change. The synchrony between fish hatching and zooplankton productivity is widely considered to be a major driver in recruitment failure, but studies considering variability in the phenology of both predator and prey are scarce. Using otolith microstructure and a time series of predator and prey abundance, we studied the influence of the mismatch between fish hatching and the timing of egg production in 2 copepod prey species on recruitment variability in lesser sandeel Ammodytes marinus, a key trophic link in the North Sea. We found that year-class strength is established during early larval development in sandeel, and depends on the degree of synchrony between hatching and Calanus helgolandicus egg production. Therefore, this study identifies the critical life stage at which year-class strength is established and provides empirical support for the mismatch hypothesis in a key forage fish.