New Satellite Tag Offers Longer Tracking of Baleen Whales

How do you track a 40-ton ocean giant without leaving a mark? Monitoring large whales is a delicate balancing act between science and safety. Satellite tags allow researchers to follow the movements of whales beyond where they can be seen. This helps us understand how whales overlap with human activity, so we can make informed conservation and management decisions. But the most durable and long-lasting tags come with a tradeoff: They implant into the whale's muscle, which can sometimes negatively impact health.

Alexandre Zerbini , a leading expert on the development of satellite tags for large whales, is bridging this gap. He is a research scientist at the University of Washington's Cooperative Institute for Climate, Ocean, and Ecosystem Studies and an affiliate at the Alaska Fisheries Science Center's Marine Mammal Laboratory . With support from NOAA Fisheries and the U.S. Office of Naval Research, he and his research team developed a "blubber-only" tag. It passes through the whale's skin but anchors into the blubber layer, stopping before it reaches lower tissue layers on the whale's body.

"We have been after a blubber-only tag for quite some time, and we are excited that Alex and his collaborators have reached this important milestone," said Eric Patterson, Cetacean and Pinniped Conservation Program Supervisor within NOAA Fisheries' Office of Protected Resources. "Whales spend most of their lives underwater, so it's incredibly challenging for us to track their larger-scale movements and migrations. Satellite tags provide critical data, and this new design produces better results than current implantable tags while being safe for the animals."

Initial Testing on Southern Right Whales

For the past several years, the research team has deployed the new tags on Southern right whales off the coast of Argentina. Southern right whales are closely related to endangered North Atlantic and North Pacific right whales , but their population is much larger. This makes them an ideal surrogate to test new tagging technology before applying it to at-risk species.

The blubber-only tag stayed attached for an average of 24 days and a maximum of 50 days, according to a new paper on the field work . This is more than double the duration of implantable dart tags currently permitted for use on North Atlantic right whales. The blubber-only tag also had no observed negative impacts on the whales' health. This engineering breakthrough can offer scientists the longer term monitoring data they need while keeping the animals as healthy and comfortable as possible.

Building a Better Tag: Small, Strong, and Safe

For large marine animals like whales, attaching an electronic tag is not straightforward. Suction cup tags that stick to the whale's skin fall off within a few hours to a few days. For longer term monitoring, scientists must use tags that break through the whale's skin and anchor into the tissue. These tags are small relative to the size of the whale, much like a human body piercing. They last longer than suction cup tags, staying on for an average of 10 days, but scientists are looking for longer term data.

Shrinking the tag into a smaller package was one of the research team's goals. At 5.3 inches, the implantable portion of the new blubber-only tag is about half the size of existing designs. It is now short enough to anchor securely in the blubber layer of many whale species-including North Atlantic right whales-without reaching the connective tissue and muscle underneath.

The blubber-only tag is not just smaller, but more robust. Other tag types have external electronic parts and extend further from the whale's skin. They can come off too soon as large whales swim in rough seas or brush up against other animals. The blubber-only tag is part of a new generation of tags with a single, integrated unit, known as a "consolidated" tag. The electronics are enclosed within a metal cylinder that is embedded inside the whale. Only the antenna and a small portion of the tag are exposed, and the antenna is stiffer and thicker. These changes fix common weak points that led tags to break, while also reducing the risk of inflammation on the animal.

For nearly 20 years, scientists have only used suction cup tags and implantable dart tags on North Atlantic right whales due to health concerns. The new blubber-only tag offers a promising alternative.

Manufacturing and Testing: From 3-D Printer to Giant Hammer

With its simplified design, the blubber-only tag's metal housing can be constructed with 3-D printing. This modern manufacturing method ensures each tag is structurally sound.

The research team subjected the design to intensive stress tests in the lab. For example, they lodged the tags in pieces of concrete and struck them with a heavy hammer. They also fired the tags into hard durometer rubber. This dense material, similar to car tire rubber, exceeds the resistance of whale skin. These tests assess whether the tags are likely to succeed in attaching to whales and withstanding the forces they are subject to when the tagged whale interacts with other individuals.

The tags held up under pressure, bending but not breaking. Most importantly, they continued to transmit location data. They were ready to be tested in the wild.

Península Valdés, Argentina: A Perfect Proving Ground

With the new tags in hand, small crews took to the water off Península Valdés, Argentina, to deploy them on Southern right whales. The whales linger in this area for months during calving season, and researchers know many of them thanks to long-term photo-identification studies. This makes for an ideal setting to follow up on the tag's performance and the health of the tagged animals over time.

Researchers went out in a 26-foot vessel to find whales to tag. The boat had to be positioned carefully so the tag could enter the whale's skin at the best possible angle.

The team tagged 35 whales between 2019 and 2023. They carefully monitored the tagged whales to ensure the wound site was healing and showed no signs of infection or other negative health effects. The whales appeared healthy in every case.

The tags proved not only safe, but reliable. Every tag the team deployed successfully transmitted location data. One unit lasted for nearly 50 days.

The Future of Whale Monitoring

Zerbini and his team are still refining and testing the design, with continued support from NOAA Fisheries and the Office of Naval Research. They aim to make it even smaller and further reduce the risk of health effects. Their progress brings the tag closer to meeting the rigorous safety standards required for use on North Atlantic and North Pacific right whales. For these small, endangered populations, it's important to minimize impacts to the behavior, reproduction, and survival of every whale.

The blubber-only tag is also applicable to other large whale species, giving researchers a more versatile monitoring tool. It is now commercially available, and permitted experts can use it to tag other baleen species with thinner blubber layers, like minke , sei , Bryde's , and Rice's whales.

Zerbini summed it up: "We have spent years working with our tag manufacturing partner to develop a new generation of tags, and we are thrilled with the progress we have made. We are happy to report successful deployments on sei whales this year, but our work is far from over. While our long-term goal is studying and better understanding these magnificent animals, our highest priority is their health and safety. We will continue refining our instruments to provide the data we need while pursuing the best possible solutions for minimizing risks to the animals we tag."