Assessment of machine learning models to identify Port Jackson shark behaviours using tri-axial accelerometers

Julianna P. Kadar*, Monique A. Ladds, Joanna Day, Brianne Lyall, Culum Brown

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Movement ecology has traditionally focused on the movements of animals over large time scales, but, with advancements in sensor technology, the focus can become increasingly fine scale. Accelerometers are commonly applied to quantify animal behaviours and can elucidate fine-scale (<2 s) behaviours. Machine learning methods are commonly applied to animal accelerometry data; however, they require the trial of multiple methods to find an ideal solution. We used tri-axial accelerometers (10 Hz) to quantify four behaviours in Port Jackson sharks (Heterodontus portusjacksoni): two fine-scale behaviours (<2 s)—(1) vertical swimming and (2) chewing as proxy for foraging, and two broad-scale behaviours (>2 s–mins)—(3) resting and (4) swimming. We used validated data to calculate 66 summary statistics from tri-axial accelerometry and assessed the most important features that allowed for differentiation between the behaviours. One and two second epoch testing sets were created consisting of 10 and 20 samples from each behaviour event, respectively. We developed eight machine learning models to assess their overall accuracy and behaviour-specific accuracy (one classification tree, five ensemble learners and two neural networks). The support vector machine model classified the four behaviours better when using the longer 2 s time epoch (F-measure 89%; macro-averaged F-measure: 90%). Here, we show that this support vector machine (SVM) model can reliably classify both fine-and broad-scale behaviours in Port Jackson sharks.

Original languageEnglish
Article number7096
Pages (from-to)1-19
Number of pages19
JournalSensors
Volume20
Issue number24
DOIs
Publication statusPublished - 2 Dec 2020

Bibliographical note

Copyright the Author(s) 2020. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • Accelerometer
  • Benthic
  • Elasmobranch
  • Epoch
  • Foraging
  • Machine learning
  • Model selection
  • Support vector machine

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