By Bob Johnson, Ag Alert
Salmon reared in rice fields grow faster and larger than those from a hatchery and are far more likely to finish the journey down the river to the Pacific Ocean, according to research underway in the Sacramento Valley.
“We found there was a significant increase in the rice field salmon that made it to the ocean, compared to hatchery-raised salmon,” said Paul Buttner, manager of environmental affairs for the California Rice Commission. “We think this could be the beginning of something like our water bird program.”
Buttner discussed the results from a pilot salmon project, and the latest additions to waterfowl habitat efforts, during the 2021 Winter Rice Grower Meeting webinar.
“Last year, our program was four times as effective as the control at getting the salmon out to the ocean,” he said. “We believe our program will get the salmon out to the ocean larger and earlier, before the predators are very active.”
The salmon project is in the early stages of learning how rice farmers can modify their fields to make them suitable for raising salmon and releasing them into the river for the journey to the Pacific.
“We are about three years into our ricelands salmon project and we already know salmon grow quickly in rice fields,” Buttner said. “We are trying to learn how to modify the fields to encourage the salmon to grow and make it back into the river.”
While the project remains in the early stages of learning how rice fields can play a role as habitat for salmon, the waterfowl habitat programs have become extensive and successful, he said.
“Our programs have exploded since 2010, especially with shorebird habitat,” Buttner said.
The California Ricelands Waterbird Foundation was created in 2016 to develop programs and raise funds to support farmers for extending use of their fields as habitat for the birds—something many growers were already doing.
The earliest and most widely adopted practice is to flood the fields after harvest, which recreates the Sacramento Valley wetlands that served as habitat for many waterfowl species for centuries.
Under the Bid4Birds program, rice farmers bid for grants to provide habitat for various waterfowl species.
“If you are a winter flooder, you qualify for $15 an acre for flooding,” Buttner said.
Another waterfowl program compensates farmers for maintaining nesting cover in the months after harvest.
There is also a phase two of the nesting cover program that compensates farmers for maintaining the cover through the summer in drought years, when they might want to consider fallowing some of their ground.
“We also have an upland bird and native pollinator habitat program,” Buttner said. As many as 230 species have been identified as using California rice fields as habitat, most of them birds.
The state’s rice fields provide bird habitat equal to 300,000 acres of wetlands, which would cost nearly $2.8 billion up front.
The Rice Commission is working in concert on the salmon project with researchers from the University of California, Davis, and Point Blue, a group of scientists who lend their expertise to private and public land managers engaged in conservation efforts.
Buttner said baby salmon raised in nutrient-rich, winter-flooded rice fields were tagged and released into the Sacramento River in the early spring of 2020, to learn how many would successfully make the trip to the Pacific.
Although only one in a hundred survived the elements and the predators to complete their journey, the result came after a low-water, drought winter when salmon survival rates were exceptionally low. The survival rate was still more than four times as many as the survivors from a control group of young salmon raised in more conventional ways.
“Our hope was to demonstrate rice field-reared fish might survive their journey out to the ocean better than those that are raised in hatcheries,” Buttner said. “We hypothesized this possible outcome based on previous studies showing that salmon grow extremely fast in rice fields because of the abundance of their natural food sources in these fields. I’m happy to say that our 2020 graduating class of young salmon did not let us down.”
Winter-flooded rice fields are naturally a rich source of nutrients for baby salmon, he said, and the research now focuses on learning how the fields can most easily be modified to allow the fish access to the river to begin their journey to the sea.
Information about the salmon project is available at calricewaterbirds.org/salmon-program.
