Oral Presentation Australian Society for Fish Biology Conference 2017

Accelerometry reveals diel activity patterns in Port Jackson sharks, Heterodontus portusjacksoni  (#91)

Julianna P Kadar 1 , Monique A Ladds 1 , Johann Mourier 1 , Jo Day 2 , Culum Brown 1
  1. Biological Science, Macquarie University, North Ryde, NSW, Australia
  2. Taronga Conservation Society, Mosman, NSW, Australia

Distinguishing the factors that influence movement variation within a species advances understanding of their behaviour and ecology. Acoustic accelerometers were used to investigate variations in activity patterns of male and female Port Jackson sharks (Heterodontus portusjacksoni) early and late in their breeding season. HD video was used to assign behaviour to root mean square (RMS) acceleration recorded by accelerometers. In order to quantify diel patterns of the sharks, we used linear regression to relate RMS acceleration output to the previously time-matched behaviours on video. To validate captive data, diel patterns from captive sharks were compared with diel movement data from free-ranging sharks. We then used linear mixed effects models to determine factors most influencing activity levels. Captive sharks showed nocturnal diel patterns, peaking in activity during the late evening before midnight and decreasing in activity before sunrise. Free-ranging sharks displayed comparable diel patterns showing captive studies can be used to understand behaviour in the wild. By directly relating RMS acoustic acceleration output to activity we show the diel, seasonal and sex-specific movement variation within this species and the corresponding activity levels of sharks in captivity.