About This Project

Baleen whales are large-bodied predators that, despite their critical role in marine ecosystems, our understanding of their physiological function remains limited. Few methods exist for studying whale health in the open ocean, but biologging tags remains a promising avenue for measuring animal physiology. This study examines the use of auscultation (i.e., a stethoscope) to non-invasively record physiological sounds, including heartbeats and respiratory patterns, from free-ranging baleen whales.

Ask the Scientists

What is the context of this research?

Baleen whales perform repeated breath-hold dives to capture small prey which are digested for energy to support their metabolic performance. Despite this extreme behavior, few methods exist for assessing the physiology that underpins the function of large whales. Existing suction cup-attached biologging tags provide detailed visual (e.g. camera) and behavioral (e.g., kinematic) data from whales, but inferring physiological function from this data is difficult and often impossible. Newer tags measure heart rate using standard ECGs, but these measurements can be disrupted by multiple sources of noise. Similarly, there are no standalone biologgers that aim to measure respiratory parameters that could reflect lung function. Auscultation presents an opportunity to monitor physiological sounds—such as heartbeats and respiratory patterns—in free-ranging whales, allowing researchers to gather important vital rate data non-invasively.

What is the significance of this project?

This project has the potential to revolutionize how we study marine mammal physiology in the wild. The use of auscultation to measure vital rates in marine mammals has been explored in a limited fashion but has been successful in measuring body sounds. By capturing sounds from their heart, lungs, and other systems, we will be able to gain reliable data on the function of a difficult-to-study taxon. This project also offers an important alternative to the limited methods that are used to assess health in free-ranging, large-bodied whales. Much of the research on cetacean health has focused on stranded individuals, individuals in human care, or data from short-term health assessments on small species. Stethoscope biologgers could represent an important novel approach for assessing health, thus highlighting an exciting frontier for the future of biologging in marine and terrestrial megafauna.

What are the goals of the project?

The overarching goal of this project is to develop a functional stethoscope tag embedded in a suction cup and successfully measure physiological sounds from a baleen whale. To execute this overall aim we will first integrate a hydrophone with battery and memory into a low-profile, waterproof, depth-rated package including depth and kinematic sensors (already in-house). We will iterate on tag attachment mechanism(s) (i.e., suction cup, adhesives) based on assessments of tag functionality, durability, and attachment in controlled salt water tanks & flume with subsurface sound sources. We will compare the stethoscope to a standard tag-based hydrophone. Then we will deploy the tested unit on at least five individual baleen whales in Monterey Bay, CA and assess the acoustic signals received compared to lab tests.