The optimal allocation of time during the diving cycle

Previous research has used a "marginal value" approach to determinehow long a diver should spend on the surface obtaining oxygenif it is to maximize the proportion of time in the foragingarea. In this paper we develop an explicit and general versionof this model and show how it results in predictions about bothtime on the surface and time under water. We also extend theanalysis to include the maximization of the net rate of energeticgain and the maximization of energetic efficiency. We show thatthe various currencies can be distinguished qualitatively interms of the way in which their predictions depend on the parametersthat characterize the animal and its environment. A generalfeature of the results is that the time in the foraging areashould first increase and then decrease as round-trip traveltime, , from the surface to the foraging area and back againincreases.