Cod in a changing climate Match-mismatch and Threshold for the North Sea cod recruitment

Abstract

Climatic changes are disrupting otherwise tight trophic interactions between predator and prey. Most of the earlier studies have primarily focused on the temporal dimension of the relationship in the framework of the match-mismatch hypothesis. Using a novel timeseries model explicitly quantifying both timing and the abundance component for predator-prey relationship, we show that timing and abundance of food affect the northsea cod (Gadus morhua) recruitment. The system shows a strong effect of matchmismatch; however, it does so in association with food abundance. The food abundance was shown to have a threshold effect on recruitment. This non-linear effect may explain the difficulties to reveal the mechanisms by which environment variability affects marine ecosystems. As such the quantification of the combined effect of abundance and timing of prey on predator dynamics will improve our ability to detect the effect of environmental changes on trophic interactions.