Listening to Gray Whales: Acoustic Monitoring
By Journey North and Michael H. Smith, Project Coordinator for Gray Whales Count
Whale Acoustics: Research led by John Hildebrand uses underwater instruments to listen to sounds made by the whales found off Southern California, Alaska, Hawaii, and Antarctica. The scientists use various acoustic recording tools and ship-based visual techniques to gather data for this study.

Setting Up the Research Project
On March 1, 2010, an exciting new phase of the Gray Whales Count project began: acoustic monitoring. scientists from Scripps Whale Acoustic Lab aboard the Channel Islands National Marine Sanctuary research vessel R/V Shearwater deployed a HARP ((High-Frequency Acoustic Recording Package). This instrument will be listening and recording underwater sounds 24/7 for two months in the Santa Barbara Channel about one mile south of Counter Point. The sound data will capture the flow of the migration, including cow/calf pairs.
Photo: Michael H. Smith

What Sounds Are Scientists Recording?
In addition to whale, dolphin and pinniped vocalizations, we will be recording all the sounds of the Coal Oil Point ("Counter Point") environment. It includes noise from vessel traffic passing over and around the migration. And it includes other noise that likely affects the whales’ migration: oil pumping at Platform Holly 1.7 nautical miles off our shore to the southwest.
The unnatural oil-platform is a physical obstacle with clanking metal and regular vessel visits to off-load workers and supplies. About every three weeks during our survey we see a huge barge towed to an arrangement of six buoys only a half mile offshore where the barge is filled with 55,000 barrels of crude oil in usually just under 24 hours. (We regularly note if whales pass outside the buoys that frame the filling process, or inside between the buoys and shore, or through the buoys. Mothers and calves often travel between the buoys and shore, and several whales have been tracked through the buoys. Very few have been noted as going through the buoys while the huge barge is in place.)
Photo:The Marine Science Institute and The Institute for Crustal Studies, University of California, Santa Barbara

Sounds also include the strange gurgles of the natural seeps of methane gas and oil that surround Coal Oil Point. these natural seeps are a strange wonder that contribute chemicals, noise, and bubbles to the water though which the whales travel. We wonder about the impact. Perhaps in the nearshore, whales may be prepared for those unpleasantries, and yet startled by the natural, sometimes explosive bubbling of the seeps.

Special Tools Record Underwater Sounds
The main acoustic tools of scientists are called acoustic recording packages (ARPs). These instruments sit on the sea floor. They can continuously record underwater sound at rates up to 1 kHz for durations over one-year. ARPs were developed by the Scripps Whale Acoustic Lab and have been used worldwide for multi-year studies of baleen whale presence. The lab is also developing another, more capable, high-frequency acoustic recording package (HARP), for recording odonotocetes (toothed whales, such as sperm whales, beaked whales, orca, dolphins, and others) at frequencies over 100 kHz.

Journal or Research Questions
  • Explore the Coal Oil Point Seep Field with this interactive map. One of the largest seep fields in the world and the best studied, the Coal Oil Point seep field is one of the natural wonders of the world. What effects do you think the seeps might have on whales and their migration path?
  • Whales, dolphins, and porpoises can send and receive underwater sound for communication or hunting purposes. Scientists observe and listen to the sounds of these marine mammals to learn about their seasonal and geographic (time-space) movements and about behavior characteristics. How do you think this information can help humans ensure a safer future for whales? What other uses might the information serve?