Researchers Dig Up New Details About Elusive Shark

May 11, 2008

Release from: CTV.ca (Canada)

A recent research expedition to the Canadian Arctic has uncovered fascinating details about the mysterious and elusive Greenland shark.

Canadian scientists took part in the study, camping out on the ice in remote locations in plywood shelters amid -25 degree temperatures, to learn more about the monsters of the deep.

Steve Campana, who has been studying Greenland sharks off the coast of Nova Scotia for years with the Bedford Institute of Oceanography, was among the researchers that spent three weeks on the ice 300 kilometres north of Iqaluit.

He said scientists' knowledge of the prehistoric-looking sharks is virtually a "black hole" because few researchers work in the cold waters where they thrive.

What they do know is intriguing. The shark's meat is poisonous and its mouth, filled with tiny, razor-sharp teeth, is located far under its body and it has almost no spine.

It is also extremely lethargic, cruising around cold-water locales at a relaxed pace, and may live up to 200 years -- though no one is really sure.

But the list of things scientists don't know about the sharks is much longer, such as how fast they grow, where they give birth and how many young they have.

"The Greenland shark is probably one of the least understood large sharks in the entire world and it's part of our ongoing mandate at the Shark Research Lab to study these Canadian sharks," Campana told CTV's Canada AM.

"And since it's a big one and such a poorly known one it was really a golden opportunity to have an expedition up to the Arctic to study them."

Among the most surprising findings was the sheer number of sharks the team caught through the ice on steel lines up to 100 metres long.

"One of the things we quickly realized is there are very, very large numbers of Greenland sharks up there in the Arctic, certainly in the Canadian Arctic and presumably elsewhere as well," Campana said.

"We couldn't come up with an absolute population number but it wouldn't surprise me if there were hundreds of thousands or perhaps even millions of these very large sharks swimming around in the Arctic."

Inuit fishermen in the Arctic had reported catching the creatures, but shark researchers had no idea how many there actually were.

Members used high quality shark-fishing gear to catch the sharks and haul them to the surface, and would then pull them onto the ice using snowmobiles.

The team fished through a five-foot diameter hole drilled through three feet of ice, and caught an average of two Greenland sharks each day.

On average, the sharks are between 2.5 and 3.5 metres in length, weighing in between 500 and 700 pounds.

If the sharks were dead when they were hauled to the surface researchers would perform an autopsy.

If they were still alive, they recorded their measurements, tagged them with satellite tracking devices and released them in order to learn more about their habits.

The tags will relay data such as the shark's average depth, the water temperature and location, before the tags release automatically in August.

Campana said the team was surprised to learn that the carnivorous sharks' stomachs, in every case, were full of food. The contents included everything from turbot fish to complete seal carcasses -- though it's not clear whether they hunted them or simply scavenged dead seals from the bottom.

He said the sharks are considered to be "apex" predators, meaning, like the Polar bear, they have no natural enemies.

The team also discovered that invariably, the Greenland sharks had a small, one-centimetre long parasite on each eye, rendering them almost completely blind.

"The odd thing is when we look at Greenland sharks in other waters ... they don't have any of these parasites at all, so we have no idea what this parasite is doing but it's an odd situation for sure."

The team will be returning to the Arctic to continue their research in late summer, after the satellite tracking tags have released and the data has been collected.