DETECTING AND MEASURING FOOD AND WATER-INTAKE IN CAPTIVE SEALS USING TEMPERATURE TELEMETRY

Methods of determining rates of feeding in marine endotherms are needed to assess impacts on marine resources. Thus, we investigated the use of temperature telemetry to measure food and water intake in captive harp seals (Phoca groenlandica) for possible application to free-ranging marine endotherms. We obtained profiles of changes in stomach temperature while the seals ingested ice, snow, seawater, and meals of fish. Ingestion of any of the substances caused a precipitous drop in stomach temperature in every instance. The rate of recovery to stable temperature was related (r2 = 0.71, P = 0.001) to the mass of the meal ingested. The stomach temperature technique provides conclusive evidence of fresh and seawater intake in harp seals and should enable detection and measurement of food and water intake in a variety of species.