Use of an acceleration data logger to measure diel activity patterns in captive whitetip reef sharks, Triaenodon obesus

摘要

Traditional telemetry methods have been used to quantify the horizontal and vertical displacement of marine species, but are unable to identify specific physical activities such as swimming or gliding, resting, foraging, or spawning. We tested the utility of an acceleration data logger to quantify activity patterns of three captive whitetip reef sharks (Triaenodon obesus) in an enclosed lagoon using internal and external attachment methods. Data obtained using both attachment methods allowed swimming and resting behavior to be differentiated. All sharks showed constant swimming for 5-14 hours post-tagging before adopting a pattern of daytime rest and nocturnal activity throughout the 6-16 day deployments. Sharks showed a diel activity pattern, spending 10-24% of their time swimming during the day, and 42-67% swimming at night. Overall, sharks spent an average of 35 +/- 11% ( mean +/- SD) of their time swimming. Mean tailbeat frequency was found to be 0.89 +/- 0.03 beats s(-1) in one shark for which it was measured. Respirometry experiments that measured the metabolic rate of two neonate whitetips showed significantly higher metabolic rates at night compared to the day. When taken in conjunction with the acceleration data, these results suggest that whitetips are nocturnally active and show diel circadian rhythms shortly after birth. Our study demonstrates that acceleration data loggers can be used to quantify activity patterns and offer promise for quantifying energy budgets of various reef sharks both in captivity and in the field.