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Researchers from Oregon State University have achieved a significant milestone by confirming the presence of two distinct shark species in Puget Sound, one of which is critically endangered.
The identification of both the broadnose sevengill shark and the endangered soupfin shark in this area—situated in the southern part of the Salish Sea—could signal important ecological shifts, according to scientists at OSU’s Big Fish Lab. These changes may reflect alterations in an inland waterway that holds substantial economic, cultural, and ecological significance.
The Salish Sea, which serves as a natural boundary between northwest Washington and British Columbia’s Vancouver Island, covers an expansive area of 6,500 square miles. As it extends into Washington, it becomes known as Puget Sound, where these sharks were captured near Olympia, close to its southernmost region.
Taylor Chapple, an assistant professor at Oregon State’s College of Agricultural Sciences, along with graduate students Jessica Schulte and Ethan Personius authored studies detailing the documentation of the broadnose sevengill and soupfin sharks, published in Frontiers in Marine Science.
The team’s work was conducted in collaboration with NOAA’s National Marine Fisheries Service and the Washington Department of Fish and Wildlife, leading to the confirmation that the broadnose sevengill shark—an apex predator capable of reaching nearly 10 feet in length—is now residing in the urbanized waters of South Puget Sound.
“Understanding the presence of the sevengill in this novel habitat is essential for comprehending the food webs within the Salish Sea,” remarked Schulte, who led the research on sevengills. “It emphasizes the necessity for ongoing monitoring and research, particularly concerning their interactions with other species that are also of conservation concern, such as salmon.”
The broadnose sevengill shark derives its name from possessing two additional gill slits compared to most shark species. This species feeds on a diverse diet, including various fish (such as rays and other sharks), crustaceans, and marine mammals. It inhabits temperate waters across the globe, with its range along the west coast of North America extending from southern Alaska down to Baja California.
Before 2021, only a single sevengill shark had ever been recorded in the Salish Sea, located at Point Roberts, Washington, near the border with Canada. However, in August 2021, unofficial reports surfaced indicating that several sevengills had been caught within South Puget Sound.
Through 10 days of field research conducted in 2022 and 2023, scientists captured nine sevengill sharks, marking a significant distance—over 190 miles—beyond their previously noted habitats. Among these, eight were males, with the largest measuring nearly 7 feet, while a female measured approximately 4 feet, 6 inches.
“Our ongoing research on this species within the waters of Oregon and Washington will enhance our understanding of its role in our vital marine ecosystems,” said Schulte.
The soupfin shark, which is the largest variety of hound shark and can grow up to 6.5 feet long, is similarly noteworthy. It was named for its historical use as a primary ingredient in shark fin soup.
“During the 1930s and 1940s, soupfin sharks faced extreme exploitation, particularly for their livers that are high in vitamin A,” Personius explained. “Despite experiencing reduced fishing pressure since then, the population has struggled to rebound and is currently being assessed for federal protection under the Endangered Species Act.”
Similar to the broadnose sevengill, the soupfin shark thrives in temperate climates around the world and serves as a top predator, consuming cephalopods and various fish species. The soupfin shark is recognized for its strong swimming abilities and can undertake migrations exceeding 1,000 miles.
During concurrent field work with the sevengill project, the team successfully caught a male soupfin shark measuring just over 5 feet.
“The Salish Sea has undergone significant changes in species abundance and composition due to industrialization and severe habitat degradation,” noted Personius. “The emergence of soupfin sharks may be linked to shifting climate conditions and modifications in prey availability.”
Following the extreme marine heat wave known as “The Blob” that occurred in 2014-2015, anchovies became a dominant forage fish species in the Salish Sea, despite being relatively uncommon in the past. Soupfin sharks are recognized as predators of anchovies.
Graduate student Maddie English is listed as a co-author on the paper concerning soupfin sharks, contributing to the collaborative efforts that included scientists from the NOAA Marine Fisheries Service and the Washington Department of Fish and Wildlife. Additionally, research associate Alexandra McInturf aided in the study of sevengill sharks.
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