Spearfishing promotes a timidity syndrome and increases the safe operating distances in fish

Abstract

19In a landscape of fear, humans are altering key behaviors expressed by wild-living animals, 20 including those related to foraging, reproduction and survival. When exposed to potentially 21 lethal human actions, such as hunting or fishing, fish and wildlife is expected to behaviorally 22 respond by becoming more timid, but proving such responses underwater in the wild has been 23 challenging. Using a rich dataset collected in situ, we provide evidence of spearfishing-induced 24 behavioral effects in five coastal fish species using the flight initiation distance (FID) as a proxy 25 of predator avoidance and boldness. We document that spearfishing promotes a timidity 26 syndrome (i.e., an increase of the average timidity of harvested populations) and that the prey's 27 wariness is influenced by individual size, level of protection offered through marine protected 28 areas and the ability to recognize the risk posed by underwater human predators. In particular, 29we show that changes in the appearance of the observer (spearfisher vs. snorkeler) modulate the 30 . CC-BY-NC-ND 4.0 International license not peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/205344 doi: bioRxiv preprint first posted online Oct. 18, 2017; risk perception among the exploited species, and these differences are more evident outside 31 marine protected areas where spearfishing is allowed. We also detected a positive correlation 32 between FID and fish size, with larger specimens (that are more likely targets of spearfishers) 33 revealing larger FID. The behavioral effects were most clearly expressed in the most heavily 34 exploited species and declined towards the less desired and less targeted ones, which may be a 35 result of learning mechanisms and plasticity and/or fisheries-induced evolution of timidity. Our 36 study reveals a trade-off where intensive spearfishing negatively affects future spearfishing 37 success through behavior-based alteration of catchability. Either rotating harvest or 38 implementation of mosaics of protected and exploited areas might be needed to manage 39 spearfishing-induced timidity in exploited stocks. 40 41