Data from: Acoustic accelerometry reveals diel activity patterns in premigratory Port Jackson sharks

Distinguishing the factors that influence activity within a species
advances understanding of their behaviour and ecology. Continuous
observation in the marine environment is not feasible but biotelemetry
devices provide an opportunity for detailed analysis of movements and
activity patterns. This study investigated the detail that calibration of
accelerometers measuring root mean square (RMS) acceleration with video
footage can add to understanding the activity patterns of male and female
Port Jackson sharks (Heterodontus portusjacksoni) in a captive
environment. Linear regression was used to relate RMS acceleration output
to time-matched behaviour captured on video to quantify diel activity
patterns. To validate captive data, diel patterns from captive sharks were
compared with diel movement data from free-ranging sharks using passive
acoustic tracking. The RMS acceleration data showed captive sharks
exhibited nocturnal diel patterns peaking during the late evening before
midnight and decreasing before sunrise. Correlation analysis revealed that
captive animals displayed similar activity patterns to free-ranging
sharks. The timing of wild shark departures for migration in the late
breeding season corresponded with elevated diel activity at night within
the captive individuals, suggesting a form of migratory restlessness in
captivity. By directly relating RMS acceleration output to activity level,
we show that sex, time of day and sex-specific seasonal behaviour all
influenced activity levels. This study contributes to a growing body of
evidence that RMS acceleration data is a promising method to determine
activity patterns of cryptic marine animals and can provide more detailed
information when validated in captivity.