Biologists attached satellite tags to the dorsal fins of endangered false killer whales in waters off Hawaii island’s Kona area on Saturday, and are now tracking the elusive group’s movements around the islands.

The group of whales, which biologists from Cascadia Research Collective call “Cluster 2,” were last spotted by researchers in August 2011. 

Researchers fixed satellite tags to the dorsal fins of three of the whales to track the movements of the group. Each tag — attached remotely with titanium darts — will provide location updates 10 to 12 times per day over the next few months

Researchers snapped photos of about 20 different individuals to compare them to their existing photo catalog, according to a news release issued by Washington stated-based Cascadia Research. 

“Every adult in the population is distinctive,” said Robin Baird, a research biologist with Cascadia Research, the nonprofit organization that is leading the research. “We’ve already discovered that one of the individuals photographed on Saturday was first documented in 1986, twenty-nine years ago.”

During a week-long field project, based out of Kawaihae, researchers had thought they might spot one of the two more commonly seen groups, named “Cluster 1” and “Cluster 3.” 

In addition to Cascadia Research, the team included biologists representing the Hawaiian Islands Humpback Whale National Marine Sanctuary as well as Kona residents Deron Verbeck, Julie Steelman and Colin Cornforth. The research project was funded by grants from the Pacific Islands Fisheries Science Center of NOAA (National Oceanic and Atmospheric Administration) Fisheries and the Hawai‘i Ocean Project, and was undertaken in collaboration with the National Marine Sanctuary, according to the release.

False killer whale “social clusters” are like killer whale “pods” — they have long-term associations of closely related individuals and tend to stick together, according to the release. Unlike the well-studied Cluster 1, which is usually seen five to 10 times each year, and Cluster 3, which is seen once or twice a year, Cluster 2 has only been seen 20 times since individuals were first documented in 1986.