The California Department of Fish and Wildlife will transport 100,000 juvenile Chinook salmon down the Sacramento River and release them into the San Francisco Bay today as part of a five-year study to determine if the method increases survival rates.
Juvenile salmon, known as smolts, must travel from their upstream spawning grounds to the ocean where they mature to adulthood before returning to their spawning grounds three years later.
But smolts face a number of dangers in their trip down the Delta, including pumps, channel diversions and predators.
The Fish and Wildlife study, now in its third year, is an attempt to help salmon avoid those dangers, said Andrew Hughan, spokesman for the Department of Fish and Wildlife.
The study is also investigating whether the method, known as “barging,” can help salmon learn the way back to their native spawning grounds by transporting them along the migratory path by water. Salmon normally use their sense of smell to find the way back to their spawning grounds.
“The idea is they travel all the way down the Sacramento River in fresh water, then they go through the brackish water, and then they go through the salt water night and acclimate,” Hughan said. “It’s called imprinting.”
Water will be circulated into the holding tank of the fishing vessel during the journey to expose the fish to the different types of water along the journey.
The smolts will be loaded into the boat upriver on Tuesday and released in the San Francisco Bay at 10 a.m. on Wednesday, where they will be swept out to sea with the tide, Hughan said.
Two other control groups of smolts will be released into the water system after being transported by trucks.
Tuesday, 100,000 smolts were released into the Sacramento River near Rio Vista. On Wednesday, a truck full of 100,000 smolts will be released into the San Francisco Bay near Tiburon.
All 300,000 fish in the study have been implanted with tiny coded wire tags so that scientists can track of which group the returning fish are part.
The Commercial Salmon Trollers Advisory Committee is supporting the study and donating the use of the fishing boat, fuel and crew time.