Aquat. Living Resour.
Volume 20, Number 4, October-December 2007Fish Aggregating Devices as Instrumented Observatories of Pelagic Ecosystems
|Page(s)||287 - 290|
|Published online||23 January 2008|
A new acoustic pH transmitter for studying the feeding habits of free-ranging sharks
Department of Zoology, Hawaii Institute of Marine Biology, University
of Hawaii at Manoa, 46-007 Lilipuna rd, Kaneohe, HI 96744, USA
2 Hawaii Institute of Marine Biology, University of Hawaii at Manoa, 46-007 Lilipuna rd, Kaneohe, HI 96744, USA
Corresponding author: firstname.lastname@example.org
Accepted: 9 February 2007
Little is known about the feeding habits of large free ranging fish, due in large part to lack of an appropriate technique for quantifying feeding variables. A previous study demonstrated that changes in gastric pH can be used as a proxy for feeding events in free-ranging sharks. Here we describe the development of a new acoustic pH transmitter to remotely measure gastric pH in sharks in the field. The transmitter consists of a dual sensor (pH and temperature) continuous pinger, and was tested in captive adult blacktip reef sharks (Carcharhinus melanopterus). The transmitter was retained in the shark's stomach for between 5–12 days. The empty stomach had a low pH (1.6 ± 0.2) and feeding induced a rapid increase in gastric pH, which was clearly distinguishable from baseline levels. Meal size showed a significant linear relationship with the magnitude of the pH changes. Measurement accuracy of the pH transmitter ranged from 0.05–0.9, although resolution of the VR100 receiver that decoded the transmitter signal was 0.1 units. The pH transmitter can be used to determine when free-ranging sharks in the field are feeding and hence quantify feeding chronology, frequency and daily ration.
Key words: Acoustic telemetry / Blacktip reef sharks / Digestion / Foraging / Gastric pH
© EDP Sciences, IFREMER, IRD, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.