Two shark species recorded for the first time in Puget Sound

Researchers at Oregon State University have provided the first scientific confirmation of two distinct shark species in Puget Sound, one of which is critically endangered.

The presence of the endangered broadnose gill shark and whale shark in the sound, the southern part of the Salish Sea, may indicate changes in what biologists at OSU’s Big Fish Lab describe as an inland waterway of great economic, cultural and ecological value.

The Salish Sea separates northwestern Washington state from Vancouver Island, British Columbia. The 16,000-square-kilometre body of water extends into Washington state as Puget Sound, and the sharks were caught near Olympia, near the southernmost point of the sound.

Taylor Chapple, an assistant professor in Oregon State’s College of Agricultural Sciences, and graduate students Jessica Schulte and Ethan Personius report documentation of the seven-gilled broadnose and soupfin fins in papers published inFrontiers of marine science.

The authors worked with partners from NOAA’s National Marine Fisheries Service and the Washington Department of Fish and Wildlife to confirm that the broadnose gill shark, a top predator that can grow to nearly 10 feet, now inhabits heavily urbanized southern Puget Sound.

“Understanding the presence of the sevengills in this new habitat is critical to understanding Salish Sea food webs, and it underscores the need for continued monitoring and research – including their relationship to other species of conservation concern, such as salmon,” said Schulte, lead author of the sevengill paper.

Broadnose gill sharks, so named because they have two more gill slits than most shark species, feed on a wide variety of prey: fish (including rays and other sharks), crustaceans, and marine mammals. They live in temperate waters around the world, and off the west coast of North America, their range extends from southern Alaska to Baja California.

Prior to 2021, only one gill shark had been observed in the Salish Sea, at Point Roberts, Washington, near the Canadian border. As of August 2021, however, anecdotal reports have indicated that several have been caught in southern Puget Sound.

Over 10 days of fieldwork in 2022 and 2023, scientists captured nine sphinx moths more than 190 miles (305 kilometers) from their previously documented range. Eight of them were males—the largest was just under 6.5 feet (2 meters)—and the female was about 4.2 feet (1.3 meters).

“Our continued research on this species in Oregon and Washington waters will help us better understand its role in our precious marine ecosystems,” Schulte said.

The same goes for the whale shark, said Personius, the study’s lead author. It is the largest species of whale shark, reaching up to 2 1/2 meters long, and is named for its use as a main ingredient in shark fin soup.

“Hollowfin sharks were exploited relentlessly in the 1930s and 1940s, particularly for their liver, which is rich in vitamin A,” Personius said. “Despite reduced fishing pressure, the species has failed to recover and is currently under consideration for federal protection under the Endangered Species Act.”

Like the broadnose whale shark, the whale shark lives in temperate waters around the world and is a top predator in any ecosystem it inhabits, feeding on cephalopods as well as a variety of fish. Whale sharks are known to be strong swimmers with migrations that can exceed 1,000 miles (1,600 kilometers).

During field work carried out in parallel with the Sevengill project, scientists captured a soup shark, a male measuring just over 1.50 metres.

“The Salish Sea has experienced profound changes in species abundance and composition, paralleling industrialization and significant habitat degradation,” Personius said. “The emergence of cupfin sharks could be a result of climate change and changes in prey availability.”

After the extreme heat wave of 2014-2015, known as “The Blob,” anchovies became a dominant forage fish species in the Salish Sea, after historically being uncommon. Tureen sharks are known predators of anchovies.

Graduate student Maddie English co-authored the whale shark study, along with scientists from NOAA Marine Fisheries Service and the Washington Department of Fish and Wildlife. Research associate Alexandra McInturf contributed to the whale shark study.