Figure 5. Net rate of energy gain as function of the percentage of time diving.

With a digestive physiology defined by Figure 4 and consecrating varying times to foraging underwater in areas with different prey densities. The model assumes that the cost of foraging underwater is 50.7 W, the cost of resting at the sea surface between dives is 23.8 W and that ingestion rate is a linear function of the time spent underwater (500 J s⁻¹ - solid line, 1000 J s⁻¹ - line with long dashes, 1500 J s⁻¹ - line with short dashes and 2000 J s⁻¹ - dotted line).