A highly migratory predator, the soupfin shark (Galeorhinus galeus) has a broad distribution across temperate waters. Historically, these sharks have been observed in estuaries around the world, but they were not thought to inhabit the Salish Sea. Despite a history of commercial fishing for this species in the northeast Pacific, there had been no confirmed reports of soupfin sharks in this region beyond a few sporadic strandings and a commercial catch in 2016. However, recent anecdotal reports from recreational fishers suggested that soupfin sharks, along with broadnose sevengill sharks (Notorynchus cepedianus), were appearing in South Puget Sound, an area over 186 miles (300 kilometers) from previous strandings.
This peaked the interest of local scientists. In response, researchers launched a multi-agency study to determine whether these reports indicated a temporary anomaly or a broader range expansion. Led by marine researcher Ethan M. Personius of Coastal Oregon Marine Experiment Station in Oregon State University, the team narrowed their study site down to Hammersley Inlet, a narrow, dynamic channel with strong currents that connects Oakland Bay to the greater Salish Sea. The geography of the area -- characterized by deep water pockets and complex topography -- made it an ideal location for monitoring potential shark activity. Using both vessel-based and shore-based fishing methods, the scientists began their quest to confirm the presence of soupfin sharks and evaluate what environmental factors might explain their occurrence. Over eight field excursions, the team deployed multi-hook droplines and shore-based tackle with bait chosen to mimic the shark's natural prey but avoid confusion with local species in dietary analyses. Carefully, the baited hooks were positioned strategically in the water column to attract sharks while minimizing unwanted interactions with scavengers. They also collected data on salinity, temperature, and tidal flow to assess potential environmental influences on shark presence.
And, boy, did it pay off.
The researchers accumulated 146 hours of fishing effort, leading to the capture of one confirmed soupfin shark! This individual, a mature male measuring 60.2 inches (153 centimeters) in total length, was identified based on key morphological characteristics, including its small second dorsal fin and distinct caudal fin structure. The shark was captured at a depth of 26.2 feet (8 meters), where the water temperature and salinity were consistent with known habitat preferences for this species. After recording morphometric data and collecting a tissue sample for genetic cataloging, the shark was tagged and released. The genetic material and capture metadata were submitted to the University of Washington's Burke Museum for future reference.
This finding marks the first scientifically confirmed presence of a soupfin shark in South Puget Sound, expanding the known range of this species and prompting further questions about its broader distribution in the Salish Sea. A vast and ecologically rich marine ecosystem in the Pacific Northwest, it spans the coastal waters of British Columbia, Canada, and Washington State (USA) and supports a diverse range of marine life, from orcas and salmon to deep-sea corals and sharks. This interconnected waterway plays a crucial role in regional biodiversity, Indigenous cultures, and coastal economies, but it also faces environmental challenges such as habitat loss, pollution, and climate change. While a single confirmed individual does not necessarily mean there is an established population here, "it is conceivable that our observation of the soupfin shark in South Puget Sound represents the initial detection of an established but cryptic population of this highly mobile species within the Salish Sea," the authors state in their published study. "However, we find this scenario unlikely." The presence of this species has important implications for the region's ecosystem dynamics: "At sufficient population levels, the presence of a novel marine predator species in the Salish Sea may influence system trophic dynamics and could necessitate consideration in ecosystem-based fisheries models currently utilized in the region."
Future research will be needed to determine whether soupfin sharks are establishing a more permanent presence in the Salish Sea or if their occurrence in South Puget Sound is due to temporary factors such as climate variability or prey availability. Continued monitoring through tagging efforts, environmental assessments, and additional fishing surveys will help clarify the drivers behind this unexpected discovery.