Monday June 12, 2023
Sierra Sun Times —
Dozens of adult sturgeon and hundreds of other large fish including threatened Chinook salmon have moved safely from receding floodwaters within the Yolo Bypass back to the Sacramento River thanks to the coordinated operation of the Fremont Weir Adult Fish Passage among the California Department of Water Resources (DWR), the California Department of Fish and Wildlife (CDFW), NOAA Fisheries and Yolo County.
Over one 48-hour period when the Fremont Weir Adult Fish Passage was opened on April 28 and 29, the facility’s fish-counting sonar counted 55 sturgeon passing through the facility to the Sacramento River to migrate upstream and spawn. Sturgeon are large fish that often measure 6 to 7 feet long and certain species can live over a century. They must reach the river to spawn, which they do only every few years.
In another 24-hour window between May 3 and 4, seven more sturgeon passed through the facility. Hundreds of other large fish and Pacific lamprey were also counted moving back to the Sacramento River during the two operational windows in April and May.
Before the passage was modified and greatly expanded in 2018, biologists rescued trapped sturgeon and other fish species in the Yolo Bypass by hand. Stress from handling could cause the fish to stop their upstream migration and not spawn. Finding ways for fish to swim through on their own – as they can do now – is highly preferable for the fish and for the safety of biologists working in the flooded conditions.