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Data from: Depth dependent dive kinematics suggest cost-efficient foraging strategies by tiger sharks

Cite this dataset

Andrzejaczek, Samantha et al. (2020). Data from: Depth dependent dive kinematics suggest cost-efficient foraging strategies by tiger sharks [Dataset]. Dryad. https://doi.org/10.5061/dryad.bg79cnp80

Abstract

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 patterns of oscillatory diving by these animals 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 hours. Using overall dynamic body acceleration (ODBA) 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 lowest possible angle and ascending at an angle of 5-14°, meaning that vertical oscillations conserved energy compared to swimming at a level depth. 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.

Methods

Tiger sharks (n=22) were captured and tagged at Ningaloo Reef, Western Australia in April and May 2017 following the methods described in Andrzejaczek et al.

In brief, tiger sharks were captured using baited drumlines and secured alongside a 5.8 m vessel with the leader and tailrope. Either a CATS (Customized Animal Tracking Solutions, Australia) Diary Tag (dimensions and weight with clamp: 15 x 4 x 6 cm and 300 g) or CATS Cam Tag (23 x 4 x 7 cm and 500 g)  were then clamped to the dorsal fins for periods of 7-48 hours (see table S1). All tags were equipped with tri-axial accelerometers, magnetometers and gyroscopes, and sensors for depth, temperature and light. All sensors recorded continuously at 20 Hz. In addition, 14 of the 22 deployments recorded video at pre-programmed hours of the day for a maximum of six hours per deployment. The tags detached from the clamp in the days following tagging, and were recovered using a handheld VHF receiver operated from a vessel.

Datasets are in the raw format downloaded from the tags. Deployment notes can be found in the supplementary information of the manuscript. 

Usage notes

Raw biologging data collected from 21 tiger sharks at Ningaloo Reef in 2017.

Datasets labelled by each individual tiger shark i.e. TS1 and TS2 are tiger sharks 1 and 2 respectively.