Southern Resident killer whales with Juliana Houghton

It’s another science + comics interview!

Name: Juliana Houghton
Job: 2nd year Masters student in the School of Aquatic and Fishery Sciences at the University of Washington
Research: Southern Resident Killer Whales

Southern Resident killer whales live in the Eastern North Pacific Ocean. They are popular with residents and tourists of the Pacific Northwest and coastal British Columbia and are of particular interest because they are extremely endangered. There are only 88 individuals left! There are so few of them that each individual has been named: they have their “scientific” names (like L72 or J26) and also their informal names (like Mike or Cookie or Granny).

Sound is important
The Southern Resident killer whales (or “SRKW” population) are fish eaters, and they use “echolocation” to find their prey. You might have heard of bats using echolocation when they hunt in the dark, and in a way, the SRKWs hunt in the dark as well. As they move deeper into the water, visibility becomes restricted, and sound is a more reliable way to interact with their environment.

echolocation

Watching whales
The Pacific Northwest is special because it is one of the few places in the world where you can go out and see these top predators in their environment, feeding and socializing with each other. One way to see them is to venture out on a whale watching tour. These tours are great for tourism and the local economy, and they also serve to increase public awareness. The downside is that the presence of whale watching boats in the vicinity of SRKWs might be disruptive: if they need to use sound to find food, then raising the background volume can interfere with that already difficult task.

Juliana’s master’s work is looking at the noise levels that SRKWs hear during busy whale-watching times. She does this by combining two unique datasets collected with researchers from NOAA Northwest Fisheries Science Center, Cascadia Research Initiative, UC Davis, and Killer Whale Tales.

The Experiment
The data for this project are acquired aboard small rigid-hull inflatable boats (RHIB) at times when whale-watching vessels are out. Using a long pole on the bow platform of the RHIB, an instrument package is carefully placed on a whale’s back using a suction cup. After a few hours of recording the ambient noise as the whale swims and dives, the suction cup is released and floats to the surface where the researchers can collect it.

tagging

While the hydrophone (or underwater microphone) records noise levels, the team on the RHIB scans the surface of the water for the tagged whale. Any time that they spot the whale, they use an instrument called a theodolite to measure the distance and horizontal angle of the whale relative to the RHIB, while also recording a description of the whale’s activity at that time (feeding, resting, communicating with other whales, etc). A second theodolite measures the locations of any other vessels within a radius of one kilometer, simultaneously recording characteristics such as vessel size, speed, and orientation relative to the whale.

ranging

Putting it all together
Juliana combines the noise level data with the vessel data to look at whether the noise levels that the whales hear is affected by the number of vessels, distance to those vessels and other factors. For example, when the tagged whale is sighted, you get a sort of snapshot of the vessels in the area. At the same time, you are listening in on the noise levels detected at the whale’s location (via the hydrophone data). This kind of information is extremely valuable because it can help guide the types of regulations that go into place for vessels in order to reduce the potential negative effects on the whales’ foraging and communication abilities.

Juliana would like to acknowledge her collaborators listed above, especially Marla Holt and Deborah Giles for their help with the acoustic and vessel location datasets.

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