Social learning enhances search image acquisition in foraging brook trout

Abstract

Brook trout feed primarily on prey items for which they have developed a search image. Periodical- ly, fish are required to update their search images to match temporal variability in prey abundance. It is currently unknown how brook trout develop search images, but there is evidence to suggest that it could be influenced by social learning, wherein a fish learns a novel behavior through observation alone. Here we demonstrate that adult brook trout use social learning to quickly develop search images for novel prey. We trained a set of demonstrators to develop a search image for canned mealworms and subsequently moved demonstrators to treatment pools that contained naive bystanders. We also had control pools that contained naive bystanders and sham demonstrators that had not been trained on mealworms. Over an 8-day period, bystanders in treatment pools consumed 68 % of meal- worms, compared to only 36 % in control pools. More- over, social learning of search images was rapid as bystanders in treatment pools began feeding on meal- worms in less than 1 day, whereas it took 7 days for bystanders in control pools to feed heavily on meal- worms. Social learning of search images confers an adaptive advantage by reducing energetic costs of foraging.