Researchers from Oregon State University have made the first scientific confirmation of two distinct shark species in Puget Sound, one of which is critically endangered. This discovery includes the broadnose sevengill shark and the endangered soupfin shark, indicating potential changes in the ecologically valuable inland waterway of the Salish Sea.
Discovery Details
The Salish Sea, which separates northwest Washington from British Columbia’s Vancouver Island, extends into Washington as Puget Sound. The sharks were found near Olympia at the southernmost point of the sound. The findings were documented by Taylor Chapple, an assistant professor at Oregon State’s College of Agricultural Sciences, and graduate students Jessica Schulte and Ethan Personius. Their research, published in Frontiers in Marine Science, was a collaboration with NOAA’s National Marine Fisheries Service and the Washington Department of Fish and Wildlife.
Broadnose Sevengill Shark
The broadnose sevengill shark, an apex predator that can grow nearly 10 feet long, is now inhabiting the heavily urbanized South Puget Sound. This shark, which has seven gill slits compared to the usual five, feeds on a variety of prey including fish, crustaceans, and marine mammals. These sharks are found in temperate waters worldwide, ranging from southern Alaska to Baja California on the west coast of North America.
Before 2021, only one sevengill shark had been confirmed in the Salish Sea. However, in August 2021, several were reportedly caught in South Puget Sound. During fieldwork in 2022 and 2023, scientists caught nine sevengills, all more than 190 miles away from their previously documented range.
“Understanding the sevengill presence in this new habitat is crucial for understanding the food webs of the Salish Sea,” said Schulte, the lead author on the sevengill paper.
Soupfin Shark
The soupfin shark, the largest species of hound shark, can grow up to 6 1/2 feet and is a key ingredient in shark fin soup. These sharks were heavily exploited in the 1930s and 1940s for their livers, rich in vitamin A. Despite reduced fishing pressure, they have not recovered and are under consideration for federal protection under the Endangered Species Act.
Like the broadnose sevengill, soupfin sharks are found in temperate waters globally and are top predators in their ecosystems, feeding on cephalopods and various fish species. The scientists caught one male soupfin shark measuring just over 5 feet during their fieldwork.
Ecological Implications
The presence of these sharks may be a result of climate change and changes in prey availability. For instance, following the 2014-15 marine heatwave event known as “The Blob,” anchovies became a dominant forage fish in the Salish Sea. Soupfin sharks, known predators of anchovies, may have followed this shift in prey availability.
“The Salish Sea has experienced pervasive shifts in species abundance and composition along with industrialization and significant habitat degradation,” said Personius.
Graduate student Maddie English and scientists from NOAA Marine Fisheries Service and the Washington Department of Fish and Wildlife contributed to the research.
