Researchers wonder if great white sharks mate off Sable Island
HALIFAX — She is 900 kilograms, has her own Twitter feed and may be cruising East Coast waters in a dizzying, long-distance quest for love.
Lydia, the aptly named “rock-star” of the great white shark world, and her smaller sidekick Betsy are being tracked off the coast of Nova Scotia in an expansive journey that researchers hope might answer a question that has bedevilled them for years — where do the apex predators go to mate?
Chris Fischer, chairman of the research group Ocearch, is leading the expedition to follow the sharks and was stunned when Lydia — a mature, four-metre great white — appeared to head to Halifax and then took a sharp right turn toward Sable Island just days ago.
The theory, he says enthusiastically, is that Lydia may be headed to the remote island to feast on seals and find a paramour with whom she can breed.
“We’ve always wondered, could Sable be a place where white sharks gather to mate? So it’s really fascinating to see both Betsy and Lydia up in that region,” he said from his home in Park City, Utah.
“We’ve always known that Nova Scotia and Newfoundland were part of the Northwest Atlantic white shark puzzle, but we just are now just gathering information trying to understand what exactly they’re doing up there.”
Fischer and his crew have been monitoring Lydia’s movements since bringing her on board the Ocearch vessel off Jacksonville, Fla., in 2013 and strapping a tracking device on her dorsal fin. Since then, she has travelled more than 57,000 kilometres over the mid-Atlantic ridge toward Europe and western Africa then back again. Her return to Nova Scotia points to a repeated pattern and a clear “migratory loop,” Fischer says, much like how the shark’s Pacific brethren behave.
Lydia showed up off the coast of Newfoundland in 2013, going deep inside the bay and close to the shorelines of Placentia Bay, before heading further out to the North Atlantic. She returned to waters south of the province the following year, leading Fischer to believe she is repeating the journey. He says males have a one-year migration pattern to mating sites, whereas females only mate every two years at the most because they have an 18-month gestation, so might not return to breeding areas as often.
The key is finding out where those areas are.
His team believes that some of that is taking place off Cape Cod, usually in the late summer and up until early winter. But, Fischer says he doesn’t think Lydia has ever been to the area.
“Does that mean that she’s finding another place to mate late in the year off Sable or Nova Scotia?” he said, adding that he is hoping to pair with Canadian scientists to bring his research vessel to the area and possibly tag more sharks in the area.
“We have to get the ship up there and figure out exactly what’s going on….This is old-school exploration, so it’s exciting.”
The information is critical to ensuring there is balance in the ocean, he said, since the sharks help manage the populations of other prey fish. He warns that without a healthy population of sharks, other species might thrive and decimate certain fish stocks.
But little is known about the species that can live to be over 70 years old and only become sexually mature after age 20, with Fischer saying they are creating a baseline of knowledge with their tracking devices. He said knowing where the sharks mate and breed could help researchers protect them and their nurseries from various threats.
“As the white shark goes, so the ocean goes — they’re the lion, they’re the balance-keeper,” he said. “They keep that second-tier predator from exploding and wiping out the whole food chain below. So it’s all about creating new data because we have so little.”
The team has tagged about 100 sharks in total and now have 20 white sharks being tracked in the North Atlantic. But Lydia appears to be a favourite, with more than 30,000 fans on Twitter under the handle ΓåòRockStarLydia and a cheeky personality that has her posting selfies while announcing her updated locations with a flurry of emoji.
“She’s super cool, she’s hip,” says Fischer with a chuckle. “She’s always on the cutting edge of humour and sassiness. She’s in the prime of her life and is a very confident shark that is cruising the ocean and owning it wherever she goes.”
Source: EU Fish stock news