ROBBINS: In an experiment a decade in the making, biologists are releasing hatchery salmon onto flooded Northern California rice fields, seeking to replenish endangered fish species while simultaneously benefiting the farmers’ business model.

At a time when environmentalists are often pitted against agribusiness in California’s water wars, conservation scientists and rice farmers are working together, trying to reclaim the great flood plains of the Sacramento River for salmon habitat.

Their task is daunting. California’s wetlands have all but disappeared, converted into farms and cities in one of the great engineering feats, or environmental crimes, of the 20th century. Now, for the cost and inconvenience of flooding their fields, rice farmers are earning goodwill and betting that a healthy salmon population will avoid new regulations to protect wildlife and keep adequate water flowing.

In recent years, biologists discovered that as rice straw decomposes in flooded fields it creates a broth rich in fish food. They call it “zoop soup.” “The zooplankton are so big and they’re so juicy, it’s like filet mignon,” said Andrew Rypel, a professor of fish ecology at the University of California Davis and lead investigator on the project.

After fattening up on their zooplankton, the salmon return to the river, swim downstream and beneath the Golden Gate Bridge on their way to sea, returning years later to spawn the next generation.

The university’s researchers have joined the California Rice Commission, the conservation group California Trout and the US Department of Agriculture on the project, seeking to reverse the trend toward dwindling fish populations as a result of human re-engineering of the state’s waterways and, in recent years, extreme drought exacerbated by climate change. “We don’t want to just sit silently while extinctions happen,” Rypel said.

Published in Dawn, February 10th, 2022