Researchers are rushing this summer to attach acoustic tags on sevengill and soupfin sharks, species only recently spotted in Salish Sea waters.
The summer wind picks up on the beach along Hammersley Inlet. Graduate students from Oregon State University’s Big Fish Lab and undergraduate students from Seattle University tie herring, cod and squid onto hooks and cast the lines. Then, they wait.
The crew passes a baby Dungeness crab from the wet sand across their palms. Students throw rocks in the water. To a bystander, they don’t seem any different from any other angler here. But they’re not fishing for trout or salmon or whatever else the others are after. They’re hoping for sharks — broadnose sevengills and soupfins specifically, populations that were reported in the Salish Sea in recent years for the first time.
The day drags on. In these quiet moments, it seems, the students may learn more about the patience fishing requires over any details of these elusive shark populations.
Then, Ethan Personius, a graduate student, feels a tug on his line. At that point, it’s all hands on deck.
Undergraduates grab a cradle made of PVC pipe and carry it to the shoreline. Taylor Chapple, principal investigator of the Oregon State University’s Big Fish Lab, lifts the shark out of the water and onto the cradle as others come and strap it in.
It’s a young sevengill, about four feet in length. While the sharks can reach up to 10 feet, the largest these students have seen in this most recent effort is about six. They cover the shark’s eyes so it calms, pour water over the gills.
“As soon as you put this towel on them, they really just kind of mellow out,” Personius said. “It calms them down.”
The researchers measure the shark, clip its dorsal fin, insert a tag surgically that will provide data for eight years, flush its stomach to see what’s inside and finally release it back into the ocean.
Acoustic tagging means attaching small, sound-emitting devices to track the sharks’ movements and behavior. These tags transmit unique signals that can be detected by underwater receivers, allowing researchers to study movement, habitat use and environmental conditions.
Since last year’s report on these sharks in the area, the researchers are rushing to get the tags out this summer while the population is local. The initial discovery caused some excitement in news media, but the real knowledge will come from the coming years of tracking and studying.
Personius and Jessica Schulte, another graduate student, are looking for movement and foraging ecology, Schulte said, essentially — where do they go and what do they eat? The tag pings the researchers throughout the Salish Sea and beyond. Sevengills and soupfins are the newest summertime addition to these waters.
“They’re potentially a new species here,” Schulte said. “They’ve never been regularly documented here, and so we’re trying to figure out what they’re doing.”
So far, the team has tagged and is currently tracking 19 sevengills in Puget Sound, with two more tags to go. Next, researchers will track the sharks over the next year or years.
Schulte says she hopes to publish a report on this acoustic tagging work late next year, but it will take years before they have a firm grasp on this population. Currently, she said, the sample size for stomach contents is limited.
In ecosystems across the world, sevengill and soupfin sharks help regulate populations and promote biodiversity by preying on a wide variety of marine animals such as fish, other sharks and seals. So, their entry into the Salish Sea holds a lot of potential implications.
A likely one, Schulte said, is prey abundance. In the past couple of decades, the sea has seen an increase in marine mammals. It’s possible this is what’s bringing these new sharks in, which would provide a service to the ecosystem because seals eat a lot of salmon that many marine species rely on.
“When people think of top predators, like top-top predators in this ecosystem, everyone thinks killer whales, but it turns out there’s a lot of sharks here in this whole region,” she said. “That’s what we’re trying to quantify and understand, is what is that role that they’re playing and how can we incorporate that into our broader understanding of this ecosystem? That way, we have can have healthier ecosystems now and into the future.”
Soupfin sharks were once abundant in open waters of the Pacific Northwest, said Personius. World War II caused a shortage of cod liver oil, so suppliers replaced it with that of soupfins and dogfish.
“It was like $13 a pound in 1930s money, so it was like (over $200) in today’s money,” he said, “so they really went after them hard and just fished them until they were almost wiped out.”
So far, he’s only caught a single soupfin in the Salish Sea — they’re out there, but harder to find. The acoustic tagging for soupfins will likely take much longer than that of sevengills.
Personius’ big question is if this new population of soupfins is just that, a new population, or if it’s a range expansion from a different population on the Washington Coast beyond the Salish Sea.
“It’s interesting to find those very open ocean sharks coming into Puget Sound,” said Lisa Hillier, senior biologist with the Washington Department of Fish and Wildlife. “And this may just indicate a shift in the ecosystem of where these animals have been, and either warm water is allowing them to come in or they’re being pushed in different directions now as their prey sources are moving, and they have to adjust to move with them.”
The discovery of the “new” population of sevengills first came via mistaken identity on a 2021 Facebook post, she said. It was reported to Hillier as someone illegally catching a sixgill shark.
“It came to myself and my colleague at NOAA, and we said, ‘that’s not a sixgill shark. That’s a sevengill shark.’”
Then, researchers with Oregon State University, NOAA and WDFW set off to verify that there was in fact a population of sevengills for a study published in June of last year in Frontiers in Marine Science, a peer-reviewed journal.
“That study was kind of the first, like, ‘oh, crap, what are they? What are they doing here?’” Hillier said. “We do a lot of different surveys in Puget Sound, and we’ve been doing them over the past 20 years, and only recently have we come across sevengill sharks. So they’re kind of coming down into South Puget Sound now and this could be due to shifts in their prey, shifts in water temperature, shifts in climate change. We don’t really know.”
So far, tagged sevengills have pinged Hillier across the Salish Sea and as far as California. Now, researchers are trying to figure out if the California population is genetically the same as the Salish Sea population.
A stronger presence of sevengills would likely help the entire Salish Sea ecosystem by preying on marine mammals who compete with humans and whales for fish, Hillier said.
“It’s a little bit of a loophole because the seals are protected from us, but it would help us out if there are more predators here,” she said. “That will bring some of those populations down and will help other components of our ecosystem, like reducing predation on and famine on other species.”
The sharks pose very little risk to humans, Hillier said. She reminds ocean-goers not to feed or pester the sharks to maintain safety for both parties.
— By Sam Fletcher