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Dolphin activity trackers will help inform conservation efforts

Dolphins and other marine animals are frequently affected by human disturbances in their habitat, including overfishing, noise pollution from shipping, construction activities, oil exploration, and navy sonar activity, as well as climate change. Although these types of disturbances can interrupt critical animal behaviors such as foraging or socializing, measuring them is difficult since the animals live under water.

Now, a team of scientists led by the University of Michigan (U-M) has developed wearable sensors for marine mammals similar to fitness trackers used by humans – known as biologging tags – that can monitor the movement and behavior of underwater creatures.

“Our goal is to use tag data to estimate foraging events, how many fish were consumed during a day, and connect that to estimates of how much energy dolphins use during the movement required to catch those fish,” said study senior author Alex Shorter, an assistant professor of Mechanical Engineering at U-M. “This is important for conservation because we can then use our approach to estimate energetic costs when these animals are disturbed.”

By attaching the biologging tags between the blowholes and dorsal fins of six dolphins, the scientists managed to noninvasively measure features such as speed, temperature, pressure, and movement, during several swimming trials. In some of these trials, the animals started from rest at a floating dock and then swam an 80-meter lap underwater at speeds up to 21 kilometers per hour. When left to swim alone, the tags tracked movements for periods ranging from 9.5 to 24 hours. One dolphin tracked for a 24-hour period swam over 70 kilometers. 

According to the researchers, this method could be extended to tag data from a variety of animals in the wild. “Our tag-based method is universally applicable to both animals in managed and wild settings, and can lead to a host of new research in monitoring the physical well-being of dolphin populations, which in turn will inform how we as humans are affecting their travel patterns, feeding requirements and lives in general,” said study lead author Joaquin Gabaldon, a postdoctoral researcher in Robotics at U-M.

“From a technological perspective, it is our hope that other researchers see the potential of dedicated on-tag speed sensing, and pursue the development of more adaptable speed sensors to enable energetics monitoring for a wider variety of marine animals.”

The study is published in the Journal of Experimental Biology

By Andrei Ionescu, Staff Writer

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