Looking for sharks deep in Puget Sound

It's no ghost; rather, it's the six-gilled shark -- a monstrosity whose lineage predates dinosaurs.

These days, the creature is nearly extinct, at least in the Northwest. But deep in the eerie depths of Puget Sound, you might be able to get a glimpse of the deep dweller.

"It's big, it's spooky," said researcher Jeff Christiansen. "You know it's a creature of the dark and it pretty much spends its entire life in the dark."

You've got to dive at least 500 feet down to see the shark. The creature, which relies on its large, green eyes to see in low-light levels, can grow up to 15 feet long and weigh 1,000 pounds.

Human encounters with the deep-water predator are rare.

"They don't hang around, they don't stay long. It's a chance encounter," said biologist John Rupp.

Most sharks only have five gills. It's the sixth gill that sets this breed apart.

Travis Swanson is a professional diver who's filmed many encounters with six-gilled sharks.

"You know, people live around Puget Sound and don't realize one of the largest sharks in the world, in our backyard," he said. "You have to respect them, you know. They're not a puppy dog."

Swanson is so good at tracking down sharks that the Discovery Channel uses him as an expert guide. I talked him into taking me along in search of this elusive creature.

Our adventure started with bait -- frozen pieces of rancid fish. The bait is anchored to the bottom of the Sound, along with an underwater camera.

"So basically we wait and watch. And when they come in, we jump in the water," said Swanson.

And if the sharks do show up, jumping in will take some guts.

"And they've got a set of teeth in those jaws that are like serrated razors," Rupp said.

"They are a meat-eating animal and they have the ability to hurt you, no different than a bear," said Swanson.

And some past divers have witnessed their ferocity first-hand.

"Divers' cameras have been bitten. The shark has snapped at people," Christiansen said.

But despite the damage they could do, experts say the six-gilled shark is not aggressive. Local researchers believe the sharks use Puget Sound as a nursing ground.

When a pregnant 14-foot shark washed up near Shelton, biologists found close to 80 pups. Sadly, none survived. But tests showed that up to eight different male sharks had fertilized her eggs.

To learn more about these mysterious creatures, researchers have put tracking tags on dozens of them.

"In the last year or so, we started getting reports," said Rupp.

The data shows sharks usually feed at the bottom of Puget Sound, but sometimes venture into shallow waters.

On my adventure with Swanson, our bait was set at 60 feet but the sharks were not the first to take it. Our underwater camera captured ratfish, small cousin to the six gill, coming to feed.

"And that's really what we want to see all the ratfish swimming around," said Swanson.

That's because once the ratfish come, Swanson said, sharks usually follow.

So we watched and waited through the dead of night -- when the six-gill is most likely to show. But our 12-hour vigil produced no sighting.

"Unfortunately, Mother Nature threw us a curve ball tonight," Swanson said.

Why weren't there any sharks around?

"There's a phenomenal number of unknowns," Christiansen said.

One thing researchers do know is that the sharks are more scarce now than they were just a few years ago.

"(We've seen) numbers as high as 40 animals at one point in time," Christiansen said. "Forty sharks on a single night in 2004 in July."

These days, instead of 40, cameras at the Seattle Aquarium capture only one or two sharks at a time, Christiansen said.

"It still just remains one big huge mystery out there," Rupp said.

But researchers Rupp and Christiansen aren't giving up. They plan to keep searching for answers about this deep dweller.

And recreational divers like myself will keep diving in, looking for that rare, chance encounter with the mysterious six-gilled shark.