Fig. 1. Harbor porpoise diving, feeding and breathing during a 43-hour DTAG deployment (hp18_134a, female 111 cm).

(A) Dive profile of the harbor porpoise with prey-capture attempts (defined by echolocation buzzes) marked in red. (B) One-min (dark red) and 20-min (light red) buzz counts. (C) Respiration rates averaged over 20-min periods (orange) and 95th percentile of MSA (a proxy for activity) averaged over 5-s (green) and 20-min periods (yellow). (D) Energy balance calculated as the cumulative difference between the energy gained from prey captures and the metabolic energy expended (estimated via respirations). Starting from a null energy balance, 0 MJ, positive energy balance is depicted in green and negative in orange. The average energy turnover per respiration is calculated following Rojano-Doñate et al., (13), and the average energy per prey capture is calculated using the estimated FMR of the individual [calculated following Rojano-Doñate et al., (13)] divided by the total number of prey-capture attempts assuming a 90% assimilation efficiency. e assumed the calorific value of prey (i.e., fish) to be 4.2 kJ g⁻¹ (67). The shaded area represents nighttime. Behavioral data for all 20 deployments are shown in fig. S9.