DOI: 10.5061/dryad.x95x69pvx
title: Recovery of reef shark populations invokes anti-predator behaviours in mesopredatory reef fishes on a coral reef

description: Natural experiments where populations of large predators have recovered
 following management initiatives offer insights into the potential for
 these animals to structure communities via consumptive and non-consumptive
 effects on their prey. Ashmore Reef, a coral reef off the coast of Western
 Australia, provides such an opportunity. Here, reef shark populations have
 increased significantly since the enforcement of a no-take MPA in 2008.
 This change has been accompanied by an increase in abundance of medium and
 large mesopredatory teleosts, but a decline in small mesopredatory
 teleosts.We explored whether these changes in abundance were accompanied
 by changes in anti-predator (non-consumptive) behaviours of mesopredators
 due to an increase in both acute and chronic risk of predation. We
 analysed videos from Baited Remote Underwater Video Systems (BRUVS)
 collected prior to enforcement of no-take status in 2004 and after
 enforcement and shark recovery in 2016 to quantify any changes in
 anti-predator behaviours of small (&lt;50 cm TL), medium (50-100 cm
 TL) and large (&gt;100 cm TL) size classes of teleost mesopredators.
 Comparisons of the effect of chronic and acute risk on the total time
 teleosts spent in the BRUVS videos, proportional time spent on activities
 associated with various risks, and foraging intensity were made both
 within years (acute risk: in videos where sharks were absent compared to
 present), and between years (chronic risk: 2004 and 2016). Our results
 indicate that both small and medium-sized mesopredatory fishes exhibit
 behaviours indicative of risk-induced trait responses (anti-predator
 behaviours) in the presence of reef sharks, and that these seem to occur
 as a joint response to the interaction of acute and chronic risks. Our
 study suggests that the decline of small mesopredatory fishes following
 the recovery of reef sharks could be due to both the consumptive and
 non-consumptive impacts of sharks as predators in this system. These
 results show that both chronic and acute risk seem to play significant
 roles in shaping behaviours of mesopredators.
description: Data were provided from a subset of Baited Remote Underwater
 Video System (BRUVS) video recordings surrounding Ashmore Reef in 2004
 (n=24) and 2016 (n=24). We analysed BRUVS videos collected prior to
 enforcement of no-take status in 2004 and after enforcement and shark
 recovery in 2016 to quantify any changes in anti-predator behaviours of
 small (&lt;50 cm TL), medium (50-100 cm TL) and large (&gt;100 cm
 TL) size classes of mesopredatory reef fishes. The dataset comprises
 behavioural measurements of the behaviours of these reef fishes. For a
 full description of the methods please see 'Recovery of Reef Shark
 Populations Invokes Anti-Predator Behaviours in Mesopredatory Reef Fishes
 on a Coral Reef' (Storm et al., Journal of Animal Ecology, 2025). The
 dataset has been analysed in R, for the code please see https://github.com/andieich/Ashmore_behaviour
description: # Recovery of reef shark populations invokes anti-predator behaviours in
 mesopredatory reef fishes on a coral reef
 [https://doi.org/10.5061/dryad.x95x69pvx](https://doi.org/10.5061/dryad.x95x69pvx) ## Description of the data and file structure ### Files and variables #### File: clean\_data.csv **Description:**  Each row represents the observation (from when a fish entered to when it left the field of view) of one mesopredatory teleost. During each observation, the below variables were recorded: ##### Variables * genus_species: Genus and species. (*Nominal*) * size_class: Size class of each mesopredatory fish species. Each mesopredatory fish species was assigned one of three size classes: ‘small’ (≤50 cm TL), ‘medium’ (50–100 cm TL), and ‘large’ (&gt;100 cm TL). (*Nominal*, *small/medium/large*) * year: Year of BRUVS drop. (*Categorial, year*) * shark_in_video: Whether a shark was in the video, yes or no. (*Binary, yes/no*) * sec_investigating_circling: The seconds a fish in an observation spent doing the 'investigating and circling' behaviour. (*Continuous, time in seconds*) * sec_passing: The seconds a fish in an observation spent doing the 'passing' behaviour. (*Continuous, time in seconds*) * sec_feeding: The seconds a fish in an observation spent doing the 'feeding' behaviour. (*Continuous, time in seconds*) * sec_total: The total seconds a fish spent in the frame (the total seconds of the observation). (*Continuous, time in seconds*) * frac_investigating_circling: The fraction of time a fish in an observation spent doing the 'investigating and circling' behaviour (as compared to the total time of observation, sec total). (*Continuous, fraction of total seconds*) * frac_passing: The fraction of time a fish in an observation spent doing the 'passing' behaviour (as compared to the total time of observation, sec total). (*Continuous, fraction of total seconds*) * frac_feeding: The fraction of time a fish in an observation spent doing the 'passing' behaviour (as compared to the total time of observation, sec total). (*Continuous, fraction of total seconds*) * bout: The number of feeding bouts the observed fish in engaged in. (*Discrete, count*) * bite: The number of feeding bites the observed fish in engaged in. (*Discrete, count*) * habitat: The habitat type the video was recorded in. (*Nominal, reef/near-reef)* * depth: The depth of the BRUVS top. (*Continuous, depth in meters)*. * log_depth: Log of the depth variable. (*Log of 'depth')* * total_time_shark_present_frame: The total time sharks were present during the observation. (*Continuous, time in seconds*) * n_frame_total: MaxN (maximum number of fish in the frame) during each observation. (*Discrete, count*) * log_n_frame_total: log of n_frame_total. (*Log of 'nframetotal')* * video: Unique video ID number for each BRUVS video. (*Nominal*) ## Code/software For code used to analyse the provided dataset, please view GitHub ([https://github.com/andieich/Ashmore_behaviour)](https://github.com/andieich/Ashmore_behaviour) ## Access information Other publicly accessible locations of the data: * [https://github.com/andieich/Ashmore_behaviour](https://github.com/andieich/Ashmore_behaviour)