John Hildebrand

Biography

John Hildebrand is a professor of oceanography at Scripps Institution of Oceanography, University of California, San Diego. He is associated with the Marine Physical Laboratory at Scripps and is an adjunct professor in the Department of Electrical and Computer Engineering. His research focuses on using sound to study marine mammals and the impact of anthropogenic sound in the ocean. Hildebrand’s lab has developed a high-frequency acoustic recording package (HARP) that is capable of long-term acoustic monitoring in remote ocean locations. These instruments are currently deployed in the Arctic, near Hawaii, off the coast of Washington and California, and in the Gulf of Mexico. HARPs have revealed new information on the behaviors and seasonal migrations of whales and dolphins. For instance, by examining the songs of blue whales, dialects were discovered that help to discriminate distinct regional populations. Hildebrand’s work also has documented that ocean noise levels from commercial shipping have increased dramatically over the past few decades, raising concerns about the potential impact of ocean noise on marine mammals. Born in San Diego, California, Hildebrand received a B.S. in physics and electrical engineering from UCSD and a Ph.D. in applied physics from Stanford University. He held a research position at SIO before joining the Scripps faculty. He has served on the Marine Mammal Commission’s board of scientific advisors and is a fellow of the Acoustical Society of America. He is a member of the Society for Marine Mammology. He is the author or coauthor of more than 150 scientific publications.

Research Interest

I am interested in how sound is used by marine mammals and how sound can be used as a tool for assessment of marine mammal populations. Recent advancements in acoustic recording technology have allowed long-term and broad-band records of underwater sound to be collected. These recordings open new windows into the behavior and distribution of marine mammals (as well as other marine organisms such as fish). Over the past decade, I have been studying how sound can be used to better understand mysticete whales, such as blue and fin whales. Some of the key results of this work are that sound may be an effective means for determining the population structure of these animals, since the songs produced by blue and fin whale have regional dialects, and these may be used by the animals as an aid for mate selection. Likewise, we have discovered that different characteristic sounds are associated with foraging and with mating behavior, and that these sounds are used with different intensity over a seasonal cycle. With the availability of expanded recording bandwidth, we have recently begun to make long-term recordings of odontocetes (toothed whales and dolphins). It has been possible to use echolocation click structure for species identification, and also to identify population structure using differences in echolocation clicks. A future challenge will be to use passive acoustic data for quantitative estimates of marine mammal abundance.