Standard Presentation (15 mins) Australian Marine Sciences Association 2022

Behaviours of Mesopredatory Coral Reef Fishes in Response to the Threat of Sharks and Humans  (#343)

Andrea Asunsolo Rivera 1 2 , Emily Lester 1 2 , Tim Langlois 1 , Brigit Vaughan 2 , Mark McCormick 3 , Steve D Simpson 4 , Mark G Meekan 1 2
  1. School of Biological Sciences and the UWA Oceans Institute, University of Western Australia, Crawley, WA, Australia
  2. Australian Institute of Marine Science, The Oceans Institute, University of Western Australia, Crawley, WA, Australia
  3. Coastal Marine Field Station, School of Science, University of Waikato, Tauranga, New Zealand
  4. School of Biological Sciences, University of Bristol, Bristol, UK

The behavioural reactions of mesopredatory fishes to the threat of potentially lethal predators and competitors have implications for the dynamics of their populations. Here, we used a snorkeler and an animated life-size model of a blacktip reef shark (Carcharhinus melanopterus), to simulate threats to mesopredatory reef fishes (lethrinids, lutjanids, haemulids and serranids). The responses of these reef fishes to these threatening treatments were compared to those generated by three non-threatening controls (a life-size model of a turtle, a PVC-pipe and perspex). Behaviours recorded by Remote Underwater Stereo-Video Systems showed that mesopredatory fishes had greater Flight Initiation Distances (FID) in response to the approach of threatening treatments (1402 ±402 – 1533 ± 171 mm) compared to the controls (706 ± 151 – 896 ±8963 mm). There was no significant difference in FID of mesopredatory fishes between the shark model and the snorkeler, suggesting that these treatments provoked similar levels of anti-threat behaviour. Additionally, FID was positively correlated with the body length of mesopredatory fishes. Our study suggests that, irrespective of the degree to which sharks and humans consume these mesopredatory reef fishes, they still elicit a consistent anti-predator response that has the potential to create risk effects.