'Never seen an orca.' Killer whale seen off Chatham likely Old Thom. What scientists said.

On the hunt for tuna about seven miles off Chatham, six Cape Codders Sunday found themselves sharing the waters with an orca that was also hunting for fish.

"It was probably about 9 or 10 in the morning," said Paul van Steensel, of Orleans. "We were dragging squid bars and we saw quite a few dolphins and other kinds of whales when, at a distance, we saw a big fin, which I thought was a sunfish because they flop over on their side."

The owner of Cape Dreams Building & Design, a custom home build and renovation company, van Steensel was treating his sons Cameron, 8, and Connor, 7, to a day on the water on his boat, the Cameron William, along with employee Chuck Van Buren of Brewster and his son Elliot, 8, and another employee, Pete Martinez of Westport.

Orca was likely Old Thom, scientists say, a frequent Cape Cod visitor

At first, he said, the orca was "quite a ways away, and then it came up again much closer to the boat. That's when I saw a white spot behind the dorsal fin and when we knew it was an orca."

It was unclear whether there was one or multiple of the marine mammals, van Steensel said, though marine scientists who have since studied the videos that were recorded believe it was a lone orca — and not a stranger to the waters off Cape Cod.

"The specific whale that was sighted — known as Old Thom — has been seen off Cape Cod several times over the past decade or so, usually in the late spring-early summer, so the fact that he was seen recently is not unusual," said Orla O'Brien, an associate research scientist in the Anderson Cabot Center for Ocean Life at the New England Aquarium.

Orca sightings in New England are still a novelty

Old Thom tends to range from Cape Cod Bay to the Gulf of Maine and the Bay of Fundy, she said. While he is a "regular," marine scientists say it's still a novelty to observe orcas in New England waters.

Last June, others of the black and white species were observed when the aquarium's aerial survey team, led by O'Brien, spotted a pod of four orcas about 40 miles south of Nantucket — an occurrence they characterized as "rare." It was the first time in 10 years of flying over the particular survey area that orcas were observed there.

When the orca came within about 70 feet of van Steensel's boat, he knew it was something special.

"I've been fishing out there for 20 years plus and I've seen a lot of whales, but I've never seen an orca," he said, adding that he's seen humpbacks and pilot whales.

His son, Connor, said he was impressed by the encounter.

"It was cool," he said, describing seeing Old Thom's "back flipper" breaching the surface.

Over about an hour, the group watched Old Thom coming and going from the surface as they continued to fish.

"The last video we got with the fin coming out at the end, he kind of rolled over on his side and splashed his tail fin," van Steensel said.

Videos generate a lot of interest

Once back ashore, his girlfriend, Taylor Grai, posted the videos they'd captured on Facebook, tagging the Woods Hole Oceanographic Institution, the Atlantic White Shark Conservancy and IFAW. Since Sunday, the videos have been viewed and shared thousands of times — at last count, as of Wednesday morning, the videos had been viewed more than 115,000 times on X, and at least 225,000 times on Facebook.

"Immediately, it went nuts," van Steensel said. "It's cool to have some kind of positive, happy news these days instead of just all the negative stuff."

Are orcas after Cape Cod's sharks?

According to the American Cetacean Society, orca behavior is driven by food, rather than regular migration routes, so sightings are generally an indication of a rich food source.

There's been some speculation among members of the public, van Steensel said, that Old Thom, and potentially others of his species, could be attracted by the high numbers of Atlantic white sharks that now visit Cape Cod through the late spring, summer and fall.

"A lot of people say that," he said, but he's not sure how much of a lure the sharks are, since last year's orca pod was seen far offshore and the sharks are hunting in near shore waters.

Also known as "killer whales," orcas — the largest members of the dolphin or "toothed whales" family, a suborder of cetaceans — are the only known marine predators of white sharks, another apex predator. Within the last two years, scientists documented orcas actively hunting white sharks off South Africa, and taking only their livers.

"Different subpopulations of killer whales tend to focus on different prey items, such as the ones that hunt white sharks off of South Africa," said O'Brien. "Other killer whales may focus on marine mammals — seals, porpoises, etc — or fish. This particular whale (Old Thom) has been observed eating fish in the past and, to my knowledge, has not been observed eating any marine mammals or sharks."

In recent years, a rebounding seal population has made Cape Cod one of the world's white shark "hot spots." Shark expert Greg Skomal, a senior biologist with the Massachusetts Division of Marine Fisheries who studies the Cape's white sharks, has linked the upward trend in white sharks to the presence of plentiful food such as seals.

There is no scientific evidence at this time, however, that the increased presence of the sharks on Cape Cod could, in turn, become equally attractive to orcas, according to the scientists. But it's also not outside the realm of possibility that warming waters resulting from climate change could bring orcas here more often as they follow shifting food sources — something that New England fishermen are already observing.

Heather McCarron can be reached at hmccarron@capecodonline.com, or follow her on Twitter @HMcCarron_CCT

Thanks to our subscribers, who help make this coverage possible. If you are not a subscriber, please consider supporting quality local journalism with a Cape Cod Times subscription. Here are our subscription plans.

This article originally appeared on Cape Cod Times: Orca spotted off Chatham during a tuna fishing outing