Preliminary estimates of lung volume capacity in free diving harbor seals (Phoca vitulina) and California sea lions (Zalophus californianus)

Diving plays a central role in the life histories of marine mammals. Marine mammals have many adaptations that allow them to store oxygen more effectively than terrestrial mammals. They also go through a number of physiological changes during their dives that allow them to further conserve and effectively utilize oxygen during periods of apnea. There have been many studies done investigating the oxygen storage and utilization of diving marine mammals, but very few that focus on the role the lungs play during dives. A two-part project was conducted at University of California Santa Cruz’s Pinniped Cognition and Sensory Systems Laboratory to collect preliminary estimates of lung volume for harbor seals (Phoca vitulina) and California sea lions (Zalophus californianus). Part one was focused on training two animals, one Pacific harbor seal and one California sea lion, to cooperatively participate in a research task designed to collect and measure the volume of air the exhale after diving. The second part of the project had a goal of collecting preliminary lung volume estimates based on data collected from the participating animals. For the first part of the project both research subjects were able to successfully complete the training and could reliably participate in the research task. Part two looked at volume of air expired for each subject and how other variables may factor into the volume of air produced for each trial. It was determined that outside variables have little to no influence on the volume of air expired by either subject. Part two also examined the difference in average volume of air expired between subjects. These results were significant and suggest that seals may dive with a larger lung volume than sea lions on average. The results of this study suggest that there may be opportunity to develop a non-invasive procedure to measure lung volume in both captive and wild live animals and the possibility of acoustic measure should be further considered