Janaury 27, 2022 — California’s native salmon have been harmed by more than a century of mining, dam building, floodplain reclamation, fishing pressure, hatchery practices, and introduced predators. These stressors have undermined the resilience of California’s native salmon to the accelerating effects of climate change, new research shows.
Researchers from NOAA Fisheries’ Northwest and Southwest Fisheries Science Centers chronicled the loss of habitat and genetic diversity that once helped salmon withstand a changing climate.
“The eggs are in fewer baskets,” said Stuart Munsch, an ecosystem scientist at NOAA Fisheries’ Northwest Fisheries Science Center and lead author of the new study published today in Global Change Biology. “The same landscape diversity in California that lets you go skiing and surfing in the same day used to support diverse salmon populations and a fishery well buffered against climate”.
“Now, that salmon diversity is mostly lost, and dams confine salmon to the hottest part of the watershed, where nonnative predators and a lack of rearing habitat reduce their survival. The result of all these stressors is that today’s salmon track climate more tightly than they used to in a warming landscape that routinely experiences drought.”
They said restoring degraded habitat and access to habitat above dams could help revive that diversity. By reopening and improving different areas, restoration can reclaim lost niches and adaptations that help spread the risk. In addition, other recovery actions such as increasing streamflow can make the restoration more effective.