Spearfishing modulates flight initiation distance of fishes: the effects of protection, individual size, and bearing a speargun
In a landscape of fear, humans are altering key behaviours of wild-living animals, including those related to foraging, reproduction, and survival. When exposed to potentially lethal human actions, such as hunting or fishing, fish, and wildlife are expected to behaviourally respond by becoming shyer and learning when to be cautious. Using a rich dataset collected in temperate rocky reefs, we provide evidence of spearfishing-induced behavioural changes in five coastal fish taxa, exposed to different levels of spearfishing exploitation, by using flight initiation distance (FID) as a proxy of predator avoidance. We detected a significant increase of mean and size effects of FID when the observer was equipped with a speargun. Such effects were more evident outside marine protected areas where spearfishing was allowed and was commensurate to the historically spearfishing pressure of each investigated taxon. Our results demonstrate the ability of fish to develop fine-tuned antipredator responses and to recognize the risks posed by spearfishers as human predators. This capacity is likely acquired by learning, but harvest-induced truncation of the behavioural diversity and fisheries-induced evolution may also play a role and help to explain the increased timidity shown by the exploited fishes in our study.