An ‘extremely unusual’ shark sighting on Cape Cod was caught on camera

Outside her living room window, Robin Rowe saw something roving in the water.

Her view overlooking the Bee’s River Marsh in Eastham, near First Encounter Beach, is perfect for catching glimpses of Cape Cod wildlife.

She watches birds there regularly. Diamondback terrapin turtles nest along the shore. Small fish swim in the tide.

But none of those creatures were the dark mass she saw skimming the surface earlier this month.

Maybe a river otter was finally making an appearance?

“I got excited because I’ve been wanting to see a river otter,” Rowe recalled recently. “So I grabbed my binoculars and my camera — my phone — and went out onto the porch to see if it popped up again. And then I saw it swim and I said, ‘This is not an otter. Definitely not an otter.'”

Rowe went down to the street and got a better view at the edge of the marsh. She took out her phone and began recording what quickly became clear was a shark — an unfamiliar sight among the marsh.

“Eventually he kind of headed out into a deeper channel and then toward the main river and, hopefully, back out into the bay,” Rowe said. “So that’s what my hope was — that he was heading towards deeper water.”

She posted about a minute-long video clip she snagged on local community Facebook pages, including one for the Eastham Chamber of Commerce, where Rowe is the communications and member services representative.

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Her intrigue did not go unmatched: Since Nov. 6, the post on that page alone had been shared over 585 times by Thursday.

And, after some consulting, Rowe learned the sight she saw was a blue shark.

Greg Skomal, the senior fisheries scientist for the state Division of Marine Fisheries, concurred.

The species is common off the coast of Massachusetts in the summer and fall but is usually found in offshore habitats, making what Rowe caught on camera a rather uncommon occurrence, he told Boston.com.

“To see one really close to shore and let alone in a marsh area is extremely unusual,” he said.

With the dropping temperatures, blue sharks migrate from New England waters and head south for the colder months, according to Skomal. He surmises the blue shark Rowe encountered may have faced a challenge other migrating sharks and some marine mammals often have to confront: making a wrong turn and getting caught in Cape Cod Bay.

Those kinds of moves have proven to be fatal errors for some. In recent years, thresher sharks have turned up dead after becoming trapped in the bay’s cold, shallow waters.

“Normally, you know, what we look for in these situations is a weak shark or a shark that appears to have been injured,” Skomal said. “We have seen animals that may have been caught in fishing gear that are injured, and they wander in close to shore because they’re weakened and they’re tired. They’re not well, they’re injured, and they end up dying in these marshes.”

But that doesn’t appear to be the case for the blue shark in Eastham.

“This one looks really healthy,” Skomal said.

Any miscalculation made by this blue shark also seems to have been corrected.

Rowe kept a close eye on the area after the sighting to make sure the shark made it back out to open waters, she said. Her husband walks the river and down near the marsh a couple of times per day, and neither him nor Rowe spotted the finned visitor again. They hoped for the best.

Encouraging large sharks to move along is, after all, difficult work, according to Skomal.

“This shark fortunately found its way out, you know. So good, healthy animals like this and because the water temperatures and the air temperature wasn’t that cold — it’s still … not December yet — we didn’t have to do anything,” he said. “The high tide came in the shark found its way out. That’s the best solution.”

Rowe said the sight was a real treat.

“You never know what you’re going to see out here in Eastham,” she said.