Canadian Marine Mystery: Cadborosaurus or Basking Shark?

The remains of a strange creature pulled from a sperm whale’s stomach off Canada’s west coast in 1937 had a head resembling a dog, a downturned nose like a camel, a reptilian body and a horse’s tail, covered in a thin white film.

Whaling station crews in Haida Gwaii assembled a wooden platform and displayed the 3-metre carcass under a white sheet, baffling veteran whalers who called it a sea monster.

A photo of the creature, dubbed the “Cadborosaurus” by locals, appeared on the front page of a local newspaper on 31 October 1937, fueling lore of a marine cryptid unknown to science.

Samples of the discovery have long disappeared, leaving only a handful of black-and-white images.

John Kirk, president of the British Columbia Scientific Cryptozoology Club, insists the carcass was an unknown species hiding in the Salish Sea, citing firsthand accounts including an interview with a flenser.

“The scientific world, of which we are a part, is always looking for excuses not to allow new animals into the catalogue. And quite frankly, I find that notion absolutely cockamamie,” he says.

One of the few pieces sent for identification was shipped to a museum in Victoria, 400 nautical miles southeast of Haida Gwaii, and disposed of after the director — not a trained zoologist — suggested it was from a foetal baleen whale.

“We lost a massive discovery here because of misidentification,” Kirk says. “And I think it’s a horror story of how flippant scientists can sometimes be in regard to these kinds of things.”

Almost 90 years later, many scientists say the images simply show a decomposing basking shark, a giant fish once common off Vancouver Island before being slaughtered to near extinction.

Because sharks have no bones, their transformation to carcass is profound; when basking sharks decay, their massive gill-basket collapses, leaving a long neck-like structure and small head, with fins that can appear furry or feather-like.

“With a long spinal cord and a small head at the end, it looks like a mythological sea serpent,” says Ben Speers-Roesch, a marine biology professor at the University of New Brunswick. “Unless you know what you are looking at or have familiarity with it, it’s not intuitive what this creature might have been.”

In 1977, the Japanese fishing trawler Zuiyō Maru pulled a creature off New Zealand that resembled a long-lost dinosaur, prompting excitement until amino acid analysis suggested it was a basking shark.

Speers-Roesch calls this the “pseudo-plesiosaur carcass” phenomenon, when decomposed basking sharks appear to have a long neck, small head and large paddles like a prehistoric plesiosaur.

He concedes the 1937 photo diverges from typical basking shark carcasses because of how it was displayed.

“The mystery has persisted because it has elements that are not as easily identifiable as a basking shark. It does look a little bit different in a couple of ways,” he says, adding that young basking sharks have rarely been found in sperm whale stomachs. “But so much of the carcass captures what we know about basking sharks and how they decompose. Even if you’re well educated, you can really make poor interpretations of what you are observing.”

With no surviving samples and only a handful of photographs, the creature’s identity can never be definitively resolved, but scientists say the real story is not a mystery species but the tragic end of one that did exist.

Amid a push to protect Pacific waters, a rare 2024 sighting of a basking shark has renewed interest in the species and the long-forgotten campaign that wiped them from coastal waters.

In 1955, the federal government devised a plan to kill the sharks using a large blade fixed to a patrol ship’s bow, called a “razor-billed shark slasher” by local media.

“Because basking sharks fed at the surface, crews could lower the blade and run them over,” says Scott Wallace, a former fisheries scientist who authored a 2007 report finding the basking shark endangered and largely extinct in British Columbia waters. “They simply cut them in half.”

The sharks’ only crime was inadvertently wandering into salmon nets.

“Anything that interacted with salmon or the salmon fishery was killed off as a way of thinking that they could again manage the ocean,” says Wallace, co-author of “Basking Sharks: The Slaughter of BC’s Gentle Giants.” “And it wasn’t long before basking sharks were added to the official ‘nuisance list’ and they became a target.”

At the same time, officials shot seals and sea lions around fishing grounds and river mouths.

In the early 1960s, Canada’s fisheries ministry installed a .50-calibre machine gun on an island, typically used against armoured vehicles, solely to kill orcas, though it was never used.

The government estimates it killed at least 413 basking sharks with the boats over 14 years, with as many as 1,500 more killed by entanglement; a brief commercial fishery for liver oil added an unknown number.

All told, as many as 2,600 sharks — more than 90% of the population — were eradicated.

Now, federal law protects basking sharks off British Columbia with the strongest wildlife protections, but Canada’s fisheries department concedes it could take 200 years for recovery.

“There are periods of time — often decades — that they [basking sharks] just disappear,” says Wallace. “And then all of a sudden, they return. Maybe it’s the ocean conditions — we really don’t know. But there is a chance, and it’s slim, that they’re still in the area, out of human view.”

Kirk rejects the basking shark explanation: “The carcass is most certainly not a basking shark. And it’s not a reptile. Whatever it is, it must be a mammal because it possesses hair and it doesn’t resemble any of the orders of marine mammals today in those waters.”

In 2010, while walking his dog, Kirk says he encountered an unknown creature in the waters where the Fraser River empties into the Salish Sea, with a pointed head and neck like a stovepipe, calling it a “breathtaking experience.”

“But I will tell you: in my nearly four decades living in the region, one thing I’ve never seen is a basking shark,” he says. “Not sure if I ever will.”

Speers-Roesch understands the allure of believing in unexplored ocean mysteries but notes human perception is error-prone, citing the “Montauk monster” — a bloated, hairless raccoon carcass mistaken for an unknown creature on Long Island. “Humans will always be curious about the unknown,” he says. “There are still profound mysteries and species in the ocean that we know very, very little about, and probably even species of relatively large animals that are yet to be discovered or described. But when you actually look at the creatures that are known to exist in the ocean, it’s even more spectacular and powerful.”