Jim Tietz was about to launch a boat off the notoriously precarious East Landing on Southeast Farallon Island as part of a safety training with some of his employees last Thursday morning when he spotted the unmistakable spouts of at least seven humpback whales. The Point Blue Farallon Island Program biologist peered through his binoculars to get a better look and realized they had company.
About twice as many killer whales were circling the humpbacks and preparing to attack.
It was the beginning of a 9-hour-long interaction just 28 miles away from San Francisco that has captivated scientists and researchers from all over the world. Tietz, who had to devote his attention to the training -- "It was pretty challenging," he told SFGATE with a laugh -- wasn't able to get another look until they took a break for lunch around noon. At that point, he contacted all of his co-workers, one of whom was able to remotely operate a webcam on the island and keep it fixed on the action. Later that afternoon, the killer whales split the humpback whales into two separate groups before targeting and chasing down an individual adult male, which is "very unusual," he said, noting they tend to go after juveniles that are easier to catch.
Tietz has been living and working on the Farallones since 2000, where he studies the migration patterns of animals ranging from bats to sharks. In the spring, he surveys LeConte's thrashers in the Mojave Desert and in the summer, tracks down oak woodland birds in the Sierra Nevada. But this sighting was unlike anything he'd ever observed.
"I've been here 23 seasons, and this is the second or third time I've seen orcas from the islands," he said over the phone Tuesday. "For me, this is a once-in-a-lifetime event."
The sighting follows the recent stranding of a juvenile humpback whale, which washed up dead near Fort Funston on Aug. 9 after officials received several reports of other deceased whales floating in the water nearby. Scientists with the California Academy of Sciences performed a necropsy of the whale and determined it had likely been attacked by an orca based on multiple lesions found throughout the carcass.
"There were semilunar bite marks and large pieces of skin and blubber missing," Moe Flannery, the academy's senior collections manager of ornithology and mammalogy, told SFGATE over the phone. "We also found non-heeled rake marks, or tooth impressions."
Earlier that week, academy biologists also learned of two other marine mammals in their response area that had washed up dead with "atypical injuries," Flannery said. One was a California sea lion with a large chunk of its skin peeled away. Another was an adult male northern elephant seal -- a particularly uncommon species in terms of stranding response, Flannery noted -- with portions of its skin and blubber torn off.
"At the time, we couldn't say conclusively that it was orca predation, but peeling skin off is not something sharks do," Flannery said. "We were very interested in finding out if there were orca in the area, and two weeks later, here's this sighting of them interacting with humpbacks."
It's "very rare" for people who respond to dead marine mammals to actually see the cause of death happening, Flannery continued. It's still not clear what happened to the male humpback whale that was singled out, but she said she wouldn't be surprised if another carcass washed up.
The presence of the orcas is likely a perfect example of the food chain in action, Flannery said. There's been an uptick in humpback whale sightings off Pacifica, which is likely linked to the high abundance of anchovy present in the waters this year as the population experiences a "boom" cycle.
"Where there is a food item like anchovy, there is a predator like humpback whales," Flannery said. "Where there is a food item like humpback whales, there's a predator like orca. It's how a healthy ocean should operate."
Still, the interaction stuck out to Nancy Black, who runs Monterey Bay Whale Watch and is the director of the California Killer Whale Project, a nonprofit dedicated to researching and collecting long-term data on the history of the species along the California coast.
"I have not seen orcas harassing humpbacks to that extent before in the over 30 years I have studied orcas in Monterey Bay," she told SFGATE in an email. "I don't know why it happened."
Black speculated the orcas may have become interested in what they thought was a calf in the group of humpback whales, noting that the orcas are part of a transient population on the West Coast, with members traveling up and down between Southern California and British Columbia to feed on seals, sea lions and other whales. She said she's seen members of the group involved in predation events on gray whale calves in Monterey Bay before.
There are three ecotypes of killer whales in the North Pacific in total, including these transient whales, as well as resident whales and offshore whales. Though their ranges often overlap, each group differs in size and appearance, tends to go after different prey, and even has separate social groups -- they don't appear to interbreed and rarely interact with one another, according to the National Oceanic and Atmospheric Administration. While they are referred to as whales, orcas are technically the largest species in the dolphin family.
After reviewing the webcam footage, Black hypothesized that there also could have been a prey item in the area that the orcas previously killed, and the humpbacks decided to interfere.
"Strangely, when we observe interactions with humpback whales and killer whales, it's usually the other way around, where the humpbacks will intently pursue killer whales if they are near any hunting events while the orcas try to kill pinnipeds or gray whales," Black said. "If humpbacks notice orcas going after prey, they often charge over and try to keep the orcas from attacking by hanging near prey, and even if the prey is dead, they will stay over and next to the carcass, trying to push orcas away from eating it."
She's hesitant to describe the event as an attack yet, as no bites, wounds or blood were observed on the humpbacks. Nevertheless, it's a fascinating observation that leaves experts with new questions about how the whales interact with one another.
"These are all very intelligent animals capable of exhibiting many diverse behaviors," Black said. "We do not know why. They live in a completely different realm than us."