Thesis
Associations between oceanographic processes and humpback whale entanglement in Southeast Queensland shark-control nets
University of the Sunshine Coast, Queensland
Bachelor of Science (Honours), University of the Sunshine Coast
2018
DOI:
https://doi.org/10.25907/00297
Abstract
East Australian humpback whales undertake lengthy annual migrations, which require sophisticated navigation abilities. These are likely influenced by the interplay between spatial memory and responses to contemporaneous environmental cues, such as water temperature and ocean currents. The physical oceanography of the Australian east coast is dominated by the East Australian Current (EAC). The EAC's inner boundary is characterised by a sharp temperature gradient, which may serve as a navigational tool for migrating humpbacks. Humpback whales encounter numerous anthropogenic threats along their migratory route, including entanglement in shark-control nets. This study provides a quantitative spatio-temporal analysis of the influence of the EAC on the probability of entanglements in shark-control nets. We use satellite-derived seasurface temperature (SST), an ocean model, and humpback whale entanglement data from the Queensland Shark Control Program, focusing on entanglements in Southeast Queensland since 2001. We present novel algorithms for detecting the EAC edge and core via Principal Components Analyses (PCA). We investigate correlations between the probability of humpback entanglement and the position of the EAC's edge and core, the maximum environmental gradient (structure) of the edge and core as determined by PCA results, in addition to SST at the shark-control net. We find that likelihood of entanglement increases when the EAC edge is less structured and closer to shore in the vicinity of the corresponding net, and that the first PC of a PCA designed to capture ocean structure explains relatively large amounts of variance. We also found an interaction indicating that more oceanic structure beyond the EAC edge lessens the influence of the edge structure on entanglement probability. Our results support the emerging idea that humpback whales use the edge of the EAC, as a navigation tool. Our findings can improve predictive capacity of future entanglements, and inform the monitoring of shark-control nets.
Details
- Title
- Associations between oceanographic processes and humpback whale entanglement in Southeast Queensland shark-control nets
- Authors
- Jessica Bolin
- Contributors
- Kylie L Scales (Supervisor)David S Schoeman (Supervisor)Carmen Piza Roca (Supervisor)
- Awarding institution
- University of the Sunshine Coast
- Degree awarded
- Bachelor of Science (Honours)
- Publisher
- University of the Sunshine Coast, Queensland
- DOI
- 10.25907/00297
- Organisation Unit
- School of Science and Engineering - Legacy; University of the Sunshine Coast, Queensland; School of Science, Technology and Engineering
- Language
- English
- Record Identifier
- 99450669502621
- Output Type
- Thesis
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