Sable Island: The perfect home for grey sealsThis Nova Scotian island is a haven for the world’s largest breeding colony of grey seals
Sable Island, one of Canada’s farthest offshore islands, is an isolated and rugged place. But for the world’s biggest breeding colony of grey seals, it’s the ideal winter home. In 1960, there were only about 8,000 grey seals in the southern Gulf of St. Lawrence. Now, more than 400,000 seals come to Sable’s beaches during the winter months to pup and breed.
Seals of Sable, a documentary from The Nature of Things, follows seal experts Damian Lidgard and Nell den Heyer as they study the marine mammals all along the windswept island. They have their theories as to why the island has become a grey seal utopia.
Location, location, location
Part of what makes Sable Island such a fantastic spot for grey seals is that it’s located close to good feeding grounds. “These animals don’t need to travel that far to access food,” says Lidgard.
It’s also got plenty of space for the seals. The remote island is a 42 kilometre–long sandbar in the middle of the ocean with wide beaches stretching along its length, giving the seals plenty of space to “haul out,” or come ashore to moult, rest, pup and breed.
Free from predators
There are no land-based predators on Sable Island, so after the seals dodge sharks lurking in the water, they find safety on its shores.
For grey seal colonies in other regions, this isn’t always the case. “There can be issues with predators, whether they be land-based predators or birds of prey,” says den Heyer.
While many fish communities in the Sable Island region have seen major population crashes, the grey seals are still flourishing. According to Lidgard, this is partially due to their eating habits.
“Grey seals are very much an opportunistic feeder in that they’re going to go feed on species which are most abundant, and that is one of the reasons why they are doing so well,” he explains.
In Seals of Sable, Lidgard attaches a camera to a few grey seals in order to see, for the first time, what they actually eat. The camera was able to record the seals as they dove deep down to hunt for a type of groundfish called sand lance, which spend most of their time buried in the sand of the seabed.
A life undisturbed
The isolation of the island, located 290 kilometres offshore from Halifax, might be the ultimate draw for grey seals. Sable Island has very few human visitors, so the seals have the beaches to themselves.
From the ’60s up until the early ’80s, Canada had organized culling and bounties, strategies to hunt down and reduce certain seal populations, notes den Heyer.
There were a few reasons why reducing seal numbers was deemed necessary at the time: it was believed the seals were depleting commercial fish stocks, damaging fishing gear and spreading nematode parasites.
Aside from small harvests, Canada has not culled the grey seal population over the last few decades, and the population has grown at its maximum rate. For animals that bear one offspring per year and can live for more than 30 years, these seals are reproducing as fast as nature will allow.
Watch Seals of Sable on The Nature of Things.