The Current Magazine Winter 2018 - Page 40


In the Central Valley of California, approximately 3360 km of state and federal levees, along with local flood protection projects, have cut off approximately 95% of historical floodplain wetlands from their river channels. We’ve effectively conquered the landscape. And the fish have suffered. Sacramento River winter-run Chinook Salmon, for one, are on the verge of extinction. Floodplains and other off-channel habitat are important refuge for salmon and provide food resources. The warm, shallow flood waters elevate phytoplankton growth; the algae turns the sunlight into sugars that nourish zooplankton, which in turn feed salmon fry. The once ample food the fish feasted on hundreds of years ago has now been taken away from them.

When rivers are connected to their floodplains, channels are able to migrate more naturally. The ‘bug buffet’ created on the floodplains would historically feed into the rivers, providing essential fish food. The food is still there today, but fish are unable to access it. The rivers have become pretty much a food desert.

The issue is that levees and other flood control infrastructure are vital for human safety. Our state capitol, Sacramento, is on a floodplain – the Yolo Bypass. Levees protect us. Equally, there's no question that agriculture is vitally important for humans. Fueled to end the water war between fish, farms, and flood control, CalTrout and UC Davis put science into action in 2011, partnering with Sacramento Valley rice farmers to grow fish on their inundated fields, deployed in floating cages. Current farm practices involve intentionally flooding rice fields in fall and early winter to aid in rice stubble decomposition. Over the course of six weeks assessing fish growth, we proved that rearing fish in managed floodplain fields results in rapid growth for juvenile Chinook Salmon; juveniles on average tripled in weight during the six-week experiment. This earned them the nickname “floodplain fatties."

The Food is

on the Floodplain