Shark Life

I once saw a Greenland Shark take a seal and I thought no more of it for years. That’s not to say that I forgot about it. No, quite the opposite. I retold the story many times when it was appropriate to talk of visiting Nova Scotia, being anchored off Sable Island, being on the edge of a marine park or other things that might bring the gruesome story back to mind. What I mean is that I hadn’t known how unusual my experience was. Or wasn’t?

A short digression with a photograph. Here are two treatments to choose from. Same sunset photo developed in two styles. Horses for courses?

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And so, back to a TV program about Greenland Sharks. I think it was broadcast at least 15 years later. And what I learned from the TV program surprised me. Science hadn’t known much about the Greenland Shark and this program revealed the discovery that they hunt seals.

There was a fisheries observer on the boat with us who confirmed that what I saw was a Greenland Shark. As I recall, his confirmation was based on size and rotundity as well as the kill itself. The shark we saw was too big to be a Great White and the snout we saw too rounded. We also had a chart with shark profiles on the bridge, much like the plane profiles from times of war. We were obliged to report Great Whites but saw none. Helpfully, lots of other sharks were on the pictorial list and one of them was the Greenland Shark. 

The sighting I had was when we were anchored off Sable Island, off Nova Scotia on the eastern seaboard where the continent shelves dramatically down to the deep ocean floor. We were having a safety meeting on the back deck of a surveying ship and I was criticised for looking away from the speaker at the meeting but it was the seals that distracted me. The seals spent time around the boat, often within twenty or thirty metres and usually just bobbing up and down. Or languidly rolling to commence a dive under the surface. What caught my attention was that several of them suddenly seemed to be racing away, swimming and splashing very unlike any seal behaviour I’d seen. It was over in a second. Calm was restored. To all but one.

A shark had broken the surface. A huge shark. A long snout seemed to be following one particular seal that suddenly stopped in its path. The shark took the frantic seal tail first, sucking it in, then spinning such that the shark’s teeth cut the blubber at the base of the seal’s neck. The shark ejected the remains of the seal; the head still attached to a skinless body was spat out into the air, a red foam marking the point where both disappeared from view.

It was so quick that I doubted the detail of what I saw. But the fisheries observer had seen it from the bridge. And my certainties, my seeing the seal’s body sailing through the air after watching the shark spinning, these were confirmed by the second witness. He’d seen it all before.

We’d been watching the Atlanta Olympics live on TV so I know it was 1996.  And we could see Sable Island Ponies among the dunes from time-to-time. Ponies that have since been elevated to Official Horse of Nova Scotia status. The island itself has become the Sable Island National Park Reserve. I said time-to-time. That’s because it was densely foggy for most of the four weeks I was there. The warm North Atlantic Current meets the cold Labrador Current coming down from the Arctic which creates a lot of fog in the summer. The day of the shark sighting was unusually clear. So clear that the even TV news weatherman told us excitedly that we might see the Perseids meteor shower; watching TV was weird because the reception would come and go as the ship rotated on its anchor.

Years later, the TV program taught me that Greenland Sharks lives mostly on the sea floor, moving very slowly as it scavenges for carrion. It’s very cold where the shark dwells. I guess it has to be very big to survive. The question is why the shark surfaces at all. Why would a shark waste the energy in a hunt that might not work? Perhaps their metabolic rate is akin to that of their distant cousins, the Bluntnose Sixgill Sharks, that became famous on the BBC Blue Planet II who encountered them cleaning up the carcass of a whale. I saw that broadcast in 2017 and it brought the Greenland Shark to mind. Is energy density the key? Food energy density and the energy needs of any animal have to match in order for the animal to survive. Apex predators like Anaconda snakes can go weeks or months without eating after one good meal; they can slow down their metabolism and risk lethargy and hibernation because they are at the top of the food chain.

And now I know that the Greenland Shark is thought to be the longest living vertebrate. They put the 80 year estimates for the Sixgills to shame. Can you imagine swimming for 200 years? All of which means there is a very good chance that the Greenland Shark I saw is still out there.

Two hundred years is a long time to live. So I presume it needs to be elusive, reclusive and downright careful too. As it says in the 2019 report, ‘direct observations of active predation have yet to be recorded’.

Academic research continues.

Which is good but odd because the 7 m 1000 kg Greenland Shark was once fished commercially at a rate of 30,000 sharks per year. All to liberate about 100 litres of oil per carcass. Even being at the apex of the food chain, the Greenland Shark has taken the evolutionary precaution of being toxic but the good folk in Iceland worked out how to dry its flesh and eat it safely.

What about grievability?

And of course, nursing mothers are the best source of shark liver oil supplements such as vitamins A, C, D, E plus zinc and selenium. So think of the 200 year lifespan next time you reach for your alkylglycerols and squalene supplements. And ask yourself are you worth it?