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ThesisCC BY-NC V4.0, Open Access
Dissertation
Understanding and Mitigating Depredation in Queensland Rod and Reel Line Fisheries
University of the Sunshine Coast, Queensland
Doctor of Philosophy, University of the Sunshine Coast, Queensland
2025
DOI:
https://doi.org/10.25907/00944
Abstract
Depredation is reported to be a significant issue faced by both recreational and commercial fisheries worldwide, impacting upon fishers using net, line, trawl and trap fishing methods. The term ‘depredation’ involves the partial or complete removal of bait, or where an organism captured by the fishing gear is partially or fully consumed by another organism before fishers can retrieve it. Depredation has been documented to be caused by a variety of marine predators, including sharks, cetaceans, pinnipeds, teleosts,
squid, crabs, octopus, and seabirds, and may result in loss of catch of between 0.9% – 26% of all fish captured in commercial and recreational fisheries worldwide.
Shark depredation of fish catches is an emerging challenge for recreational, commercial, and charter fishers globally, influenced by a complex combination of environmental, behavioural, and operational factors. This research was focused on understanding the significance of shark depredation in tropical and sub-tropical fisheries in Queensland, Australia, aiming to identify species responsible, the frequency of depredation events, and the factors that influence such interactions. A multi-modal approach was
employed, combining genetic analysis, underwater observation, citizen science, and shark movement monitoring. We were able to visualise shark behaviour, identify responsible species by region and season, and quantify depredation rates across different regions off the Australian east coast for the first time. The effectiveness of shark deterrents was also evaluated to address sustainability concerns of target and key secondary fish species.
This research significantly contributes to the development of evidence-based strategies to mitigate shark depredation, with direct implications for the management and ongoing sustainability of Australian fisheries resources. Without a better understanding of depredation, increased fishery-induced cryptic mortality may impact assessment and management efforts, with possible undetected declines in stock levels and an increasing costs to operators. Based on the results reported herein, we make recommendations regarding adaptive management changes including spatial and temporal adaptations in fishing effort, along with the implementation of portable deterrents to target depredating species in certain areas. Overall, this research has significantly contributed to guiding the future directions in the sustainable management of Australian fisheries resources.
Details
- Title
- Understanding and Mitigating Depredation in Queensland Rod and Reel Line Fisheries
- Authors
- Jaeden Vardon - University of the Sunshine Coast, Queensland, School of Science, Technology and Engineering
- Contributors
- Bonnie Holmes (Principal Supervisor) - University of the Sunshine Coast, Queensland, School of Science, Technology and EngineeringChristine L Dudgeon (Co-Supervisor) - University of the Sunshine Coast, Queensland, School of Science, Technology and EngineeringAdam Barnett (Consultant Supervisor) - James Cook UniversitySamuel Williams (Consultant Supervisor)Jess A T Morgan (Consultant Supervisor) - Department of Primary Industries
- Awarding institution
- University of the Sunshine Coast, Queensland
- Degree awarded
- Doctor of Philosophy
- Publisher
- University of the Sunshine Coast, Queensland
- DOI
- 10.25907/00944
- Organisation Unit
- School of Science, Technology and Engineering
- Language
- English
- Record Identifier
- 991146540002621
- Output Type
- Dissertation
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