Scientists Track Endangered Fin Whales with Earthquake Sensors

What do earthquakes and whales have in common? They can both be tracked with the same type of sensor. Scientists are actually using seafloor seismometers in order to chart the movements of endangered fin whales.

Fin whales are the second largest animal on Earth--and also one of the least understood. With their sleek, streamlined bodies, they race through the world's seas; because of their global range, it's been hard to pin down their specific habits and their patterns of travel. Feeding on krill, small school fish and squid, this species has baleen plates which it uses to strain the water.

Now, though, researchers may be learning a bit more about these elusive whales. Seafloor seismometers record vibrations, which means that the data that they record can be an inexpensive and non-invasive way to monitor the whales through their calls.

The devices themselves were actually installed about a decade ago as part of a project to monitor tremors on the Juan de Fuca Ridge, a seismically active zone more than a mile deep off of the Washington coast. After a year, though, researchers realized that they weren't just recording earthquakes.

"Over the winter months, we recorded a lot of earthquakes, but we also had an awful lot of fin whale calls," said principal investigator William Wilcock, a UW professor of oceanography, in a news release. In fact, these whale calls, which overlapped with the seismic data, "were kind of a nuisance."

Yet he soon realized that these recorded whale calls were an untapped source of data to monitor the fin whales. He and other researchers compared the calls recorded by eight different seismometers, analyzing more than 300,000 whale calls total. By examining these whale calls, the researchers were able to follow animals' paths through the instrument grid.

In the end, the researchers were able to create 154 individual fin whale paths and discovered three categories of vocalizing whales that swam south in winter and early spring of 2003. They also found a category of rogue whales that traveled north in the early fall, moving faster than the other groups while emitting a slightly higher-pitched call.

"One idea is that these are juvenile males that don't have any reason to head south for the breeding season," said Dax Soule, a UW doctoral student in oceanography who compared the whale calls, in a news release. "We can't say for sure because so little is known about fin whales. To give you an idea, people don't even know how or why they make their sound."

The findings have given researchers a little more insight about this elusive, endangered whale. They hope that in the future, they can continue to track these whales and better understand how food availability may be linked to their presence.

The findings are published in the Journal of the Acoustical Society of America.