Researchers off Hawaii's Kona coast on Friday documented a rare sighting of killer whales, including at least two that were playing host to hitchhiking remoras (see top photo).
There were four individuals in the group: a male, an adult female, and two sub-adults. Three of the four were outfitted with satellite tags, and a biopsy sample was collected from one of the cetaceans.
Cascadia Research Collective stated on its Facebook page that this was only its third killer whale encounter in the 14 years the group, which is based in Olympia, Wash., has been conducting studies in Hawaiian waters.
"These are the first satellite tags we've deployed on killer whales in Hawaiian waters, and we think the first tags deployed on this species in the tropical Pacific, so we are excited about learning where these whales spend their time," Cascadia stated on its website.
The 15-day research project ended Friday, but some of the scientists went back to sea on Sunday and re-located the four killer whales, plus three others, and witnessed a predation event involving a thresher shark.
Cascadia also posted a chart showing the movements of two of the three tagged killer whales (posted below).
Cascadia added that there is no evidence of a resident population of killer whales in Hawaiian waters: "Whales seen around the main Hawaiian Islands are likely part of a wide-ranging population that inhabits the central Pacific.
"There are some physical differences from killer whales seen in Hawaii compared to the well-known populations along the west coast of North America. The saddle patch (the gray area below and behind the dorsal fin) is very narrow in killer whales in Hawaii, and not very bright."
Scripps Institution of Oceanography researchers also participated in the two-week tagging project, which also featured encounters with sperm whales, pygmy killer whales, false killer whales, Cuvier's beaked whales, and rough-toothed dolphins.
–Photos: Top image shows killer whale with at least five remoras hitching a ride. Second image shows an adult female and a sub-adult. Credit: @Robin Baird/Cascadia Research Collective