One snack before the road: Egg cannibalism in post-spawning Downs herring

This dataset gathers information about the biometry, reproduction status, and stomach content analysis of adult Downs herring collected by professional fishermen during the 5 weeks (November - December 2022) of the 2022 winter spawning season. Herring migrates to the Eastern English Channel in winter to spawn. Earlier, it feeds during spring and summer in the north of the North Sea, and stops feeding when gonad maturation starts. Consequently, feeding resumption after spawning is crucial. The project leading to this dataset investigated the impact of reproduction on feeding behavior by monitoring jointly reproductive status of fish (through  gonadosomatic index calculation) and diet resumption (by analyzing stomach content both with visual identification of preys and automated analyses of preys images), notably monitoring the changes in stomach vacuity over the 5 weeks. 
This dataset confirms that (1) automated image analysis of preys is powerful to document herring diet, (2)  pre-spawning individuals stop feeding (as all stomachs are empty), and that feeding resumption occurs only after spawning and (3) that cannibalism on eggs is a strategy adopted by post spawning herring to cope with the need of a quick energetic input, before engaging in back migration.