Albion Environmental, a Santa Cruz research consulting firm, and researchers from Santa Clara University analyzed thousands of fish bones excavated from a 19th century indigenous village on Mission Creek, a historical Guadalupe River tributary long since buried under modern urban development. In an abstract of their research, which has not yet been published, the authors describe using DNA sequencing on 55 confirmed salmonid bones. They identified 52 as belonging to steelhead trout and three as Chinook salmon. Whether Chinook occurred naturally in the South Bay’s watersheds has been debated for years, and the new research seems to settle the matter. While the salmon could have been caught in the ocean or Bay and transported to the native village, the near absence of any other marine species in the assemblage of bones found onsite suggests that the human occupants were isolated from marine resources and that the fish swam to them. Moreover, the Chinook bones came from small fish, presumably young salmon born in the river, explains Rick Lanman, the lead author of the unpublished manuscript. The watershed’s habitat type seems to have been suitable for Chinook, according to the paper. The authors also point out that, “despite recent extreme drought years and major flood control-related concretization of the river,” Chinook continue to spawn in the Guadalupe River system in small numbers. Should the scientific community accept the results, the natural range of the Chinook will expand deeper into the urban landscape of the Bay Area, presenting new goals for conservationists and new challenges for government officials and water agencies. In the words of the study’s authors, “Watershed planning should incorporate restoration of this important aesthetic and commercial marine resource.”

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2018 Chinook spawning sites in the heart of Silicon Valley. Image courtesy of South Bay Clean Creeks Coalition
 

New archaeological evidence from the South Bay strengthens the case that Chinook salmon spawned naturally in the Guadalupe River.

Albion Environmental, a Santa Cruz research consulting firm, and researchers from Santa Clara University analyzed thousands of fish bones excavated from a 19th century indigenous village on Mission Creek, a historical Guadalupe River tributary long since buried under modern urban development. In an abstract of their research, which has not yet been published, the authors describe using DNA sequencing on 55 confirmed salmonid bones. They identified 52 as belonging to steelhead trout and three as Chinook salmon. Whether Chinook occurred naturally in the South Bay’s watersheds has been debated for years, and the new research seems to settle the matter. While the salmon could have been caught in the ocean or Bay and transported to the native village, the near absence of any other marine species in the assemblage of bones found onsite suggests that the human occupants were isolated from marine resources and that the fish swam to them. Moreover, the Chinook bones came from small fish, presumably young salmon born in the river, explains Rick Lanman, the lead author of the unpublished manuscript. The watershed’s habitat type seems to have been suitable for Chinook, according to the paper. The authors also point out that, “despite recent extreme drought years and major flood control-related concretization of the river,” Chinook continue to spawn in the Guadalupe River system in small numbers. Should the scientific community accept the results, the natural range of the Chinook will expand deeper into the urban landscape of the Bay Area, presenting new goals for conservationists and new challenges for government officials and water agencies. In the words of the study’s authors, “Watershed planning should incorporate restoration of this important aesthetic and commercial marine resource.”

About the author

A native to San Francisco, Alastair Bland is a freelance journalist who writes about water policy in California, rivers and salmon, marine conservation and climate change. His work has appeared at NPR.org, Smithsonian.com, Yale Environment 360 and News Deeply, among many other outlets. When he isn't writing, Alastair is likely riding his bicycle uphill as fast as he can.

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