Innovative Technology Enhances Tracking of Endangered Eagle Rays

In a significant advancement for marine conservation, researchers have successfully developed a new sensor tag capable of tracking endangered eagle rays for extended periods, revealing critical insights into their behavior and habitat. This innovative approach, led by Dr. Matt Ajemian from Florida Atlantic University’s Harbor Branch Oceanographic Institute, overcomes previous technological limitations that have hindered the study of these elusive creatures.

The whitespotted eagle ray, a coastal predator measuring up to six and a half feet wide, is currently classified as Endangered by the International Union for Conservation of Nature (IUCN). Prior to this breakthrough, tracking rays had proven challenging due to their unique anatomical features. Unlike sharks, eagle rays possess flat bodies that lack a sturdy dorsal fin, making traditional attachment methods ineffective. Their velvety skin also complicates the use of adhesives and darts, resulting in limited tracking durations—historically, less than ten studies have documented the fine-scale behavior of pelagic rays, compared to hundreds for sharks.

Dr. Ajemian and his team designed a compact and lightweight tag that includes a camera, motion sensors, hydrophone, satellite pinger, and acoustic beacon. The team employed a novel attachment method using silicone suction cups and a soft strap that loops through the animal’s spiracles, allowing for quick installation while minimizing harm. The results from sea trials conducted off Bermuda were promising, with ten tagged rays retaining their devices for an average of 21 hours; one individual managed to keep the tag for an impressive 59.2 hours—three times longer than previous attempts.

The data collected from these tags has provided unprecedented access to the underwater activities of eagle rays. Observations indicate that these rays navigate various marine environments, including seagrass beds, coral rubble, and reef ledges, with dives recorded at depths of up to 72 feet. Additionally, the tags captured audio of feeding behaviors, confirming the consumption of clams. Dr. Cecilia Hampton, a doctoral researcher involved in the project, noted the significance of the sound data, which identified feeding behaviors even when the video feed was turned off to conserve battery life.

The use of artificial intelligence (AI) further enhances the analysis of the data collected. The tag’s accelerometer and gyroscope recorded 50 data points per axis every second, and a supervised Random Forest model accurately classified behaviors such as swimming and feeding with remarkable precision. This method not only scales across species but also promises to increase the efficiency of future tags by potentially eliminating the need for cameras, thus extending battery life.

The implications of this research extend beyond mere observation. Eagle rays play a crucial role in marine ecosystems by controlling populations of conchs and clams. Understanding their feeding patterns and habitats is essential for effective conservation strategies. The data collected from the new tags can inform management practices, leading to the establishment of no-take zones and adjustments in dredging schedules to avoid disrupting peak foraging times.

As the research progresses, there is potential for further innovations. Slimmer sensor suites with longer battery lives could transform eagle rays into mobile habitat monitors, collecting vital data on noise, temperature, and water quality across coastal regions. The success of this tagging method may also extend to other smooth-skinned species, such as cownose rays and manta rays, facilitating a broader application of this technology in marine conservation efforts.

The study detailing these findings has been published in the journal Animal Biotelemetry, marking a new chapter in the effort to protect endangered marine species. As marine ecosystems face increasing threats from human activity, the ability to track and study these animals in their natural habitats is more important than ever. Future research will continue to build on these findings, providing deeper insights into the complex interactions within marine environments and the conservation of vulnerable species.