Synchronous human-dolphin foraging increases fishing success despite prey unpredictability

Abstract

Abstract Foraging theory predicts that individuals adjust their behaviour in response to environmental conditions and prey availability. One solution to finding and capturing unpredictable prey is social foraging, yet it remains unclear whether its benefits arise from behavioural coordination itself or simply from predators co-occurring under favourable environmental conditions. We examine how environmental conditions shape the outcome of social foraging between predators—dolphins and human fishers—that forage together on patchy, ephemeral migratory mullet schools. Using fisher catch as our empirical measure of foraging success, we test whether mullet abundance and catch are influenced by local environmental conditions, or whether social foraging buffers fishers from fluctuations in prey availability. Using confirmatory path analysis, we investigate the links among environmental conditions, mullet abundance, predators’ abundance, and synchronous behaviour to determine their relative influence on prey capture. Our results indicate two pathways to higher prey capture. First, fishers catch more mullet when these are more abundant (typically under northerly winds), but environmental conditions do not predict dolphin-fisher foraging synchrony. Second—and independently—more dolphins are present during flood tides, which leads to more fishers, more synchronous foraging, and more mullet caught. These moment-by-moment analyses demonstrate that behavioural coordination, rather than prey availability or shared environmental responses alone, is the primary driver of fisher success. More broadly, our results provide a mechanistic understanding of how social foraging can buffer predators against environmental variability, highlighting the role of coordination in overcoming prey unpredictability.