Doctor of Philosophy, University Of Western Australia (2019)
Bachelor of Science, James Cook University (2013)
Bachelor of Science, University Of Western Australia (2014)
Barbara Block, Postdoctoral Faculty Sponsor
- Regional movements of satellite-tagged whale sharks Rhincodon typus in the Gulf of Aden ECOLOGY AND EVOLUTION 2021
Regional movements of satellite-tagged whale sharks Rhincodon typus in the Gulf of Aden.
Ecology and evolution
2021; 11 (9): 4920–34
To gain insight into whale shark (Rhincodon typus) movement patterns in the Western Indian Ocean, we deployed eight pop-up satellite tags at an aggregation site in the Arta Bay region of the Gulf of Tadjoura, Djibouti in the winter months of 2012, 2016, and 2017. Tags revealed movements ranging from local-scale around the Djibouti aggregation site, regional movements along the coastline of Somaliland, movements north into the Red Sea, and a large-scale (>1,000 km) movement to the east coast of Somalia, outside of the Gulf of Aden. Vertical movement data revealed high occupation of the top ten meters of the water column, diel vertical movement patterns, and deep diving behavior. Long-distance movements recorded both here and in previous studies suggest that connectivity between the whale sharks tagged at the Djibouti aggregation and other documented aggregations in the region are likely within annual timeframes. In addition, wide-ranging movements through multiple nations, as well as the high use of surface waters recorded, likely exposes whale sharks in this region to several anthropogenic threats, including targeted and bycatch fisheries and ship-strikes. Area-based management approaches focusing on seasonal hotspots offer a way forward in the conservation of whale sharks in the Western Indian Ocean.
View details for DOI 10.1002/ece3.7400
View details for PubMedID 33976859
View details for PubMedCentralID PMC8093710
- Behavior and Ecology of Silky Sharks Around the Chagos Archipelago and Evidence of Indian Ocean Wide Movement FRONTIERS IN MARINE SCIENCE 2020; 7
- A review of a decade of lessons from one of the world's largest MPAs: conservation gains and key challenges MARINE BIOLOGY 2020; 167 (11)
- Depth-dependent dive kinematics suggest cost-efficient foraging strategies by tiger sharks ROYAL SOCIETY OPEN SCIENCE 2020; 7 (8)
- Individual variation in residency and regional movements of reef manta rays Mobula alfredi in a large marine protected area MARINE ECOLOGY PROGRESS SERIES 2020; 639: 137–53
Depth-dependent dive kinematics suggest cost-efficient foraging strategies by tiger sharks.
Royal Society open science
2020; 7 (8): 200789
Tiger sharks, Galeocerdo cuvier, are a keystone, top-order predator that are assumed to engage in cost-efficient movement and foraging patterns. To investigate the extent to which oscillatory diving by tiger sharks conform to these patterns, we used a biologging approach to model their cost of transport. High-resolution biologging tags with tri-axial sensors were deployed on 21 tiger sharks at Ningaloo Reef for durations of 5-48 h. Using overall dynamic body acceleration as a proxy for energy expenditure, we modelled the cost of transport of oscillatory movements of varying geometries in both horizontal and vertical planes for tiger sharks. The cost of horizontal transport was minimized by descending at the smallest possible angle and ascending at an angle of 5-14°, meaning that vertical oscillations conserved energy compared to swimming at a level depth. The reduction of vertical travel costs occurred at steeper angles. The absolute dive angles of tiger sharks increased between inshore and offshore zones, presumably to reduce the cost of transport while continuously hunting for prey in both benthic and surface habitats. Oscillatory movements of tiger sharks conform to strategies of cost-efficient foraging, and shallow inshore habitats appear to be an important habitat for both hunting prey and conserving energy while travelling.
View details for DOI 10.1098/rsos.200789
View details for PubMedID 32968529
View details for PubMedCentralID PMC7481696
- Tiger shark predation on large ocean sunfishes (Family Molidae) - two Australian observations ENVIRONMENTAL BIOLOGY OF FISHES 2019
- Biologging Tags Reveal Links Between Fine-Scale Horizontal and Vertical Movement Behaviors in Tiger Sharks (Galeocerdo cuvier) FRONTIERS IN MARINE SCIENCE 2019; 6
Cryptic habitat use of white sharks in kelp forest revealed by animal-borne video.
2019; 15 (4): 20190085
Traditional forms of marine wildlife research are often restricted to coarse telemetry or surface-based observations, limiting information on fine-scale behaviours such as predator-prey events and interactions with habitat features. We use contemporary animal-attached cameras with motion sensing dataloggers, to reveal novel behaviours by white sharks, Carcharodon carcharias, within areas of kelp forest in South Africa. All white sharks tagged in this study spent time adjacent to kelp forests, with several moving throughout densely kelp-covered areas, navigating through channels and pushing directly through stipes and fronds. We found that activity and turning rates significantly increased within kelp forest. Over 28 h of video data revealed that white shark encounters with Cape fur seals, Arctocephalus pusillus pusillus, occurred exclusively within kelp forests, with seals displaying predator evasion behaviour during those encounters. Uniquely, we reveal the use of kelp forest habitat by white sharks, previously assumed inaccessible to these large predators.
View details for PubMedID 30940023
- Cryptic habitat use of white sharks in kelp forest revealed by animal-borne video BIOLOGY LETTERS 2019; 15 (4)
- First Insights Into the Fine-Scale Movements of the Sandbar Shark, Carcharhinus plumbeus FRONTIERS IN MARINE SCIENCE 2018; 5
Temperature and the vertical movements of oceanic whitetip sharks, Carcharhinus longimanus
2018; 8: 8351
Large-bodied pelagic ectotherms such as sharks need to maintain internal temperatures within a favourable range in order to maximise performance and be cost-efficient foragers. This implies that behavioural thermoregulation should be a key feature of the movements of these animals, although field evidence is limited. We used depth and temperature archives from pop-up satellite tags to investigate the role of temperature in driving vertical movements of 16 oceanic whitetip sharks, Carcharhinus longimanus, (OWTs). Spectral analysis, linear mixed modelling, segmented regression and multivariate techniques were used to examine the effect of mean sea surface temperature (SST) and mixed layer depth on vertical movements. OWTs continually oscillated throughout the upper 200 m of the water column. In summer when the water column was stratified with high SSTs, oscillations increased in amplitude and cycle length and sharks reduced the time spent in the upper 50 m. In winter when the water column was cooler and well-mixed, oscillations decreased in amplitude and cycle length and sharks frequently occupied the upper 50 m. SSTs of 28 oC marked a distinct change in vertical movements and the onset of thermoregulation strategies. Our results have implications for the ecology of these animals in a warming ocean.
View details for DOI 10.1038/s41598-018-26485-3
View details for Web of Science ID 000433291300054
View details for PubMedID 29844605
View details for PubMedCentralID PMC5974137
The ecological connectivity of whale shark aggregations in the Indian Ocean: a photo-identification approach
ROYAL SOCIETY OPEN SCIENCE
2016; 3 (11): 160455
Genetic and modelling studies suggest that seasonal aggregations of whale sharks (Rhincodon typus) at coastal sites in the tropics may be linked by migration. Here, we used photo-identification (photo-ID) data collected by both citizen scientists and researchers to assess the connectedness of five whale shark aggregation sites across the entire Indian Ocean at timescales of up to a decade. We used the semi-automated program I3S (Individual Interactive Identification System) to compare photographs of the unique natural marking patterns of individual whale sharks collected from aggregations at Mozambique, the Seychelles, the Maldives, Christmas Island (Australia) and Ningaloo Reef (Australia). From a total of 6519 photos, we found no evidence of connectivity of whale shark aggregations at ocean-basin scales within the time frame of the study and evidence for only limited connectivity at regional (hundreds to thousands of kilometres) scales. A male whale shark photographed in January 2010 at Mozambique was resighted eight months later in the Seychelles and was the only one of 1724 individuals in the database to be photographed at more than one site. On average, 35% of individuals were resighted at the same site in more than one year. A Monte Carlo simulation study showed that the power of this photo-ID approach to document patterns of emigration and immigration was strongly dependent on both the number of individuals identified in aggregations and the size of resident populations.
View details for DOI 10.1098/rsos.160455
View details for Web of Science ID 000389244400021
View details for PubMedID 28018629
View details for PubMedCentralID PMC5180127