It sounds like a simple question, right? How do you measure a whale? Well, the more you think about it, the more you will come to understand that it is not easy at all to measure such a large and moving animal. Well, two Ph.D. students, KC Bierlich and Walter Torres came up with a way of measuring whales. And, of course, they used drones to do so.
The students reasoned that you would measure whales one section at a time.
“It sounds like a simple thing, but how do you measure a whale?” said Bierlich, who is pursuing a Ph.D. in Marine Science and Conservation, according to an article from Duke. “You can’t jump in the water and put a measuring tape around it. You can’t grab it and pull it back in the lab; it’s huge. Before drones came along, the field was limited to measuring whales that had stranded on beaches, were intentionally killed, or were photographed from airplanes, which can be challenging, expensive, and dangerous. Drones allow for a safer, affordable, and efficient way to non-invasively take measurements of whales in real time.”
To measure a whale, they launch a drone from an inflatable boat, fly it over the marine mammal and try to get high-resolution images when the whale swims close to the surface.
Bierlich studies how much fat reserve humpback whales need to develop while they’re in their Antarctic feeding grounds, to survive their annual migration to the breeding areas around the equator. To do this precisely he needs to measure the whale’s length relative to whale’s width at various parts of its body.
“I want to know how healthy a whale is, how fat it is—a fat whale is a happy whale,” he said. “By being able to take a length and divide that length into widths and see how fat it is down the body will help me assess how healthy it is. ImageJ is really good at measuring very detailed things in an image, but it can’t divide a length based on widths.”
So, Bierlich decided to partner up with Torres a fellow student to develop their own software that could do exactly that. The program, MorphoMetrix, was released as open-source software last year and the duo published a paper about it in January. The software can be used to measure any animal not just whales.
“I have over 300 animals I’m using in my analysis, which is almost unheard of for this type of work,” Bierlich said. “So this software has been great for quickly going through a lot of images. It’s very fast to be able to measure what I want, and I can measure a bunch of different things other than just the total length and width. I can measure different parts of the whale—like parts of the skull—things we really couldn’t do. Now we can measure live animals and compare populations to see if this population is more healthy, or if they may have different diets based on their skull size. There are all these new questions that we can now answer.”
Bierlich demonstrated the software at a conference of marine mammal researchers and received enthusiastic responses. He and Torres plan to update the software in the future based on feedback from other researchers. Bierlich is also working with former Duke student Clara Bird, now a graduate student at Oregon State, to develop an add-on tool that automatically calculates other size-related metrics and organizes the measurements made in MorphoMetrix.
Bierlich hopes that his open-source software will help to establish a standard set of tools in this new area of research where drones are used to get accurate measurements of animals in the wild.
“I want it to be collaborative—that’s the whole point for making the software open source, so it’s available for everybody,” he said. “It’s been really fun to talk with these other labs to collaborate together and build the best practices for everyone to follow and make it easier for people in the future.”
Images courtesy of KC Bierlich