DETECTION AND TELEMETRY OF FEEDING EVENTS IN FREE SWIMMING SHARKS AND TUNA
An ability to directly measure feeding events in top predators (e.g., tuna, sharks) would represent a major advance in quantifying energy flow through marine ecosystems. An appropriate device must detect these events over prolonged periods and be able to withstand large pressure changes. We hypothesized that physical changes occurring during ingestion and digestion should be quantifiable by measuring Bulk Electrical Impedance across paired electrodes. We successfully demonstrated this using a prototype tag (Wildlife Computers Inc.) to record impedance changes occurring inside the stomachs of free swimming captive sharks over multiple feeding events. Feeding and digestion produced characteristic changes in electrical impedance of the stomach contents identifiable as 5 successive phases: (1) Empty stomach, (2) Ingestion, (3) Chemical ‘lag’ phase, (4) Mechanical ‘chyme’ phase, and (5) Stomach emptying phase. The duration of the chyme phase was positively related to meal size. We recently observed these same phenomena in yellowfin and bluefin tuna. We are now deploying prototype tags in wild animals and adding accelerometry capabilities to assist in interpretation of feeding events. Preliminary results from these recent events will be presented.
Holland, K., Hawaii Institute of Marine Biology, USA, email@example.com
Meyer, C., Hawaii Institute of Marine Biology, USA, firstname.lastname@example.org
Location: 310 Theater
Presentation is given by student: No