Using Drones and Tags to Study Rice’s Whales

NOAA Fisheries listed the Rice's whale, previously known as the Gulf of Mexico Bryde's whale, as an endangered species under the Endangered Species Act in 2019. Since then, they have been a top research priority for NOAA scientists. Even with dedicated research efforts, many questions remain about the behavior and ecology of these whales, including how they feed, their diving patterns, and when they vocalize.

This summer, NOAA Fisheries partnered with Ocean Allianceand Marine Conservation Researchto investigate some of these questions. Together, we deployed suction cup tags from drones onto Rice's whales in the Gulf of Mexico to learn more about these endangered whales. Ocean Alliance recently used this techniquefor other baleen whales, but this is the first time this method has been used on Rice's whales.

In late August 2024, the team set sail on board the Song of the Whale, a 70-foot sailboat and floating research station. The team included scientists and staff from NOAA Fisheries, the University of Miami's Cooperative Institute for Marine and Atmospheric Studies, Marine Conservation Research, and Ocean Alliance. They spent 21 days at sea searching for whales to tag. The team successfully tagged seven Rice's whales and collected approximately 65 hours of dive and movement data. These data will increase our knowledge of Rice's whale diving patterns and fine-scale movements in their core distribution area.

Some tags also recorded videos-providing a "whale's-eye view" of their activities. The team collected video footage from three of the whales and observed them diving, feeding, and navigating the underwater landscape.

Benefits of Suction Cup Tags

Marine scientists often use tags to track animal movement. For an endangered species like the Rice's whale-with approximately 50 individuals remaining-it's important to minimize risks to the animals while studying them. This is where suction cup tags are beneficial. The tags temporarily adhere to the whale's skin and pop off after a few hours or days-without injuring the animal.

The tags recorded data about each whale including:

• Movement, such as pitch and roll
• Direction (heading)
• Acceleration
• Depth
• Calls

In the past, we've deployed these tagsby approaching whales in a small boat and tagging the whales with a long pole. This process can be difficult, requiring very calm weather and close coordination between the tagger and the boat driver. The researchers also need to be careful not to cause too much disturbance to the animals. Due to these complexities, we have only collected data from two Rice's whales using this method.

Matthew Bowers was the lead scientist for the mission.He stated, "In four prior cruises, we successfully tagged two whales using poles, so it's a significant breakthrough to be able to tag seven animals on our first cruise using the drone approach."

This is where the drones, and our valuable partnership with Ocean Alliance, come in. Ocean Alliance provided the drones, equipment, and pilots for operating them. Ocean Alliance developed this drone-based tag deployment method and has successfully tagged multiple species of fast-moving whales that present similar challenges as Rice's whales. The speed, maneuverability, and bird's-eye view provided by drones provide an advantage over traditional tagging methods and cause less disturbance to the whales.

Annie Gorgone, a marine mammal field biologist, described the experience saying, "It was remarkable to see how effectively this tagging method worked. This expedition will mark a monumental step forward in our understanding of these whales."

One added benefit of using suction cup tags is that they are a non-invasive method for collecting genetic information. Once the tags are recovered, the team swabs the suction cups and brings the swab back to the lab for genetic analysis. These data can help scientists further refine population estimates, identify the sex of individuals, and even identify individual whales using their unique genetic sequence.

How To Tag a Whale with a Drone

The team set out into the Gulf of Mexico to survey the whales' core distribution areafor individuals to tag. Their habitat extends all around the Gulf's continental shelf break in waters 100 to 400 meters deep, and most Rice's whale sightings have been in the northeastern Gulf. This is also where long-term passive acoustic monitoring instruments have detected Rice's whales on more than 90 percent of days, so the team focused their efforts there.

Once a whale is spotted, a pilot from our partners at Ocean Alliance launches a drone. The drones are equipped with a custom-designed system to carry a tag and release it on command.

The drone operator carefully pilots the drone in the whale's direction until it is hovering about 100 feet over the whale. It takes a lot of skill to match the whale's direction and speed. Once they are synced up with the whale's movement, the pilot slowly lowers the drone to about 30 feet above the whale and waits for it to surface. When the whale comes up to breathe, the pilot releases the tag from the drone. After a short fall-plop!-the tag's suction cups stick to the whale's back and it is taken along for the ride.

The tags sometimes come off on their own when they lose suction-typically after about a day. During this study, these tags stayed on the whales anywhere from 15 minutes to 18 hours. The team can also program how long the tag stays on the whale and when it is released from the whale. Once it detaches, the tag floats to the surface of the ocean where the science team can track its immediate location using radio telemetry. Then, they sail to its location, scoop it up, and download the critical data housed inside.

"We were extremely excited to have the opportunity to collaborate on this project and use our drone tagging expertise for what we think is an ideal use case - a data-deficient, difficult-to-approach, hard-to-study species,"said Chris Zadra, director of drone programs at Ocean Alliance."We are proud to demonstrate the successful use of this tool with Rice's whales and aid in furthering our understanding of this enigmatic species."

Results and Implications

The data collected on this expedition specifically focused on understanding Rice's whale behavior, including:

• Dive behavior
• Feeding ecology
• Vocalizations
• Energetics

A huge bonus with these tags is the ability to "listen" to the whales as they swim underwater. These data will help improve our understanding of their acoustic behavior, including:

• Which whales produce different call types
• How often they produce calls
• How their calling relates to foraging and social behavior

In addition, this will help our acousticians interpret call detections from long-term passive acoustic recordings.

The team will analyze the photographs of the whales sighted during this survey and add them to our photo-ID database. By photographing and observing the same whales through time, we can learn more about the life history and movement patterns of the whales.

"Being able to successfully use this emerging and non-invasive technique to more efficiently apply tags to these whales is a game changer,"said Jenny Litz, marine mammal branch chief at the Southeast Fisheries Science Center."The data we can collect from these tags is critical to understanding their foraging behavior, energetic needs, and call behavior. We are so grateful to our partners and excited about the data collected and the possibilities this new tagging method provides."

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