A team of researchers in Washington state were surprised after they recently caught a young broadnose sevengill shark in Puget Sound — a species that normally gives birth further south.
According to B.C. shark expert Meaghen McCord, a live juvenile has never been captured and recorded in that area before. It comes after the first scientific recording of the species in South Puget Sound, a series of narrow inlets in the Salish Sea off Olympia, Wash., about two years ago.
“Sharks only move for a very few reasons — food, reproduction, that’s pretty much it,” said McCord, executive director of the B.C. chapter of the Canadian Parks and Wilderness Society.
“The sevengills are potentially looking for new habitats to have their pups, with warmer, shallower waters and fewer predators.”
While other shark species are commonly found in the area, the new discovery has researchers looking into why broadnose sevengills — which can grow up to three metres in length and can live to almost 50 years old — are showing up and potentially giving birth in the area, and what this means for ecosystem health.
Biologist Lisa Hillier from Washington’s Department of Fish and Wildlife says their research began after a photo of a sevengill shark in Puget Sound was posted to Facebook in 2021.
Once the photo was verified, a collaboration began between Hillier’s department, Oregon State University and the National Oceanic and Atmospheric Administration to see if they could catch one of the sharks in the area.
“On our very first sampling day, we caught a male and a female — very surprising to us,” Hillier said.
They also found and tagged a female last Thursday — the second female tagged so far.
As of Monday, the team has tagged a total of 13 broadnose sevengill sharks. The goal now is to tag a broader population to monitor where and when the sharks are moving.
Changing oceans
Hillier said climate change is pushing sharks in different directions as the ocean warms.
“It may be that it’s getting too hot in some places and it may be that the food is shifting,” said Hillier. “Or perhaps they just were able to sense that there’s an abundant prey source for them up in this area.”
That has implications for biodiversity, McCord said.
“We know that the ocean is changing,” she said. “There’s warming … and we do have cause for concern, just broadly about the health of the ocean and what that means for biodiversity, and how we’re managing biodiversity along the coastline here.”
While she’s still unsure what sevengill sharks will mean for the local sixgill sharks that already inhabit the area, Hillier said more sharks in the Puget Sound ecosystem isn’t a bad thing.
They’ll help reduce the population of marine mammals, such as seals and sea lions, which are currently really high in the area, she said.
“What they really do is help weed out the weak and sick and help animals move around so they’re not overeating,” Hillier said.
In terms of human-shark interactions, both Hillier and McCord say not to worry.
Hillier said there are already 13 species of sharks that inhabit Puget Sound and there’s never been an incident. Sevengills are low risk in terms of danger to humans and people would actually be lucky to see one, she added.
Other sharks migrating
Broadnose sevengills aren’t the only type of shark that appear to be moving far into the Salish Sea.
While looking for more of the species in 2022, the researchers also caught a soupfin shark.
“This animal also is not known to be this deep into South Puget Sound, but with the changing dynamics of our ecosystems … we think that maybe they’re following some food in the area,” Hillier said.
They’ve only caught one so far, but have heard anecdotal information that others have been caught.
Even though soupfins can migrate hundreds of kilometres, McCord was even more surprised by the discovery of this shark, which can grow up to two metres long and live to the age of 60.
“Typically, the soupfin shark is … often found in the open ocean and coastal waters — finding these sharks within the sound [is] very surprising.”
There have also been recent sightings of the giant basking shark, the world’s second-largest fish, off the B.C. coast.
“Seeing the basking shark in the Salish Sea recently was really exciting and not expected because they are so rare in our waters nowadays,” McCord said, explaining that they were hunted until the late 1970s.
“Seeing these three species in such a close time to each other is interesting,” she said. “It could just be happenstance, or it could be a signal that there’s other things happening in the water.”