Wild Harbor Porpoise Heart Rate and Behavior

The impressive breath-hold capabilities of marine mammals are facilitated by both enhanced O2 stores and reductions in the rate of O2 consumption via peripheral vasoconstriction and bradycardia, coined the dive response. Many studies have focused on the extreme role of the dive response in maximizing dive duration in marine mammals, but few have addressed how these adjustments may compromise the capability to hunt, digest and thermoregulate during routine dives. Here we use DTAGs which record heart rate together with foraging and movement behaviour to investigate how O2 management is balanced between the need to dive and forage in five wild harbour porpoises that hunt thousands of small prey daily during continuous shallow diving. Dive heart rate was moderate (median minimum 47-69 bpm) and relatively stable across dive types, dive duration (0.5-3.3 min), and activity. A moderate dive response, allowing for some perfusion of peripheral tissues, may be essential for fuelling the high field metabolic rates required to maintain body temperature and support digestion during diving in these small, continuously-feeding cetaceans. Thus, despite having the capacity to prolong dives via a strong dive response, for these shallow-diving cetaceans, it appears to be more efficient to maintain circulation while diving: extreme heart-rate gymnastics are for deep dives and emergencies, not everyday use. This dataset is associated with a manuscript submitted to Proceedings of the Royal Society B investigating diving heart rate of wild harbor porpoises. There are 13 files. 1) McDonaldetal_Porpoise2021_ColumnHeader_Def.csv - provides column name definitions for all the file types. 2) DiveSummaryStats_Porpoise_2021.csv - Heart rate, activity and dive summary data for all dives analyzed in the paper. All five porpoises combined3) IntervalSummaryStats_Porpoise_2021.csv - Summary heart rate and activity data for 5 s intervals during the bottom of the dive. All 5 porpoises combined.4-8) Files that end with HR. The instantaneous heart rate data for the 5 porpoises in the study. File name includes porpoise ID. 9-14) Files that end with MSA. A MSA data file for each of the 5 porpoises with minimum specific acceleration data at 25 Hz. File name includes porpoise ID.Large raw and processed tag data are available upon request to Birgitte McDonald ([e-mail])