Abstract
Sensory information drives animal behaviour and thus understanding perception is integral to species conservation and management, including the mitigation of human-shark interactions. A recent study on white sharks (Carcharodon carcharias) showed that manipulating the visual cues of objects that resemble natural prey reduces the likelihood of sharks biting the objects, potentially offering new technology to reduce shark-bites. These experiments used artificial counterilluminated prey (seal-shaped decoys) towed behind a boat. However, white sharks also target static objects. Moreover, there is a risk that bright lights may be attractive to other potentially dangerous shark species. In this study, we evaluated the potential of counterillumination for shark-bite mitigation by comparing interactions of white and bull sharks (Carcharhinus leucas) with static counterilluminated decoys against non-counterilluminated control decoys. Lighting of different intensities arranged as horizontal stripes on the underside of oval-shaped decoys were tested. White sharks interacted less with counterilluminated decoys compared to control decoys, at the medium and high light intensities. However, they interacted more when the stripes were dimmest or the lights were on but covered. Whereas bull sharks were unaffected. Counterillumination technology shows promise for reducing human-shark encounters with white sharks when sufficiently bright, while posing minimal risk of attracting bull sharks.
Acknowledgements
We are indebted to the Oceans Research Institute and thank the many interns and staff for their help, we would especially like to thank Justin McCarthy, Sasha Dines, Olivia Seeger and Dylan Irion. The study was funded by the Australian Research Council (Linkage Project LP160100333).
Funding
The study was funded by the Australian Research Council (Linkage Project LP160100333).
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Competing interests
The counterillumination designs described herein are encompassed by International Patent Application PCT/AU2024/050500 (WO/2024/234058).
Ethics
This study was carried out with the approval of the Macquarie University Animal Ethics Committee (ARA 2017/022) in strict accordance with the guidelines of the Australian Code of Practice for the Care and Use of Animals for Scientific Purposes (8th Edition, 2013). The work was also approved by the South African Department of Environmental Affairs: Biodiversity and Coastal Research, Oceans and Coasts Branch (Permit: RES2019/26) and the Southern Province, New Caledonia (309–2020/ARR/DDDT).
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Information
Supplementary Information 1. (download DOCX )
Supplementary Video 1.
Supplementary Video 2.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Reprints and permissions
About this article
Cite this article
Ryan, L.A., Gennari, E., Slip, D.J. et al. Behavioural responses of white and bull sharks to static counterilluminated decoys.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-68093-6
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-026-68093-6
Keywords
- Shark vision
- Shark bite mitigation
- Prey detection
- Sensory conservation
Source: Ecology - nature.com
