Floodplain farm fields benefit juvenile salmon

June 9, 2017 by Nina Erlich-Williams
Rice fields managed as floodplains during winter can create surrogate wetland habitat for native fish. Credit: Carson Jeffres/UC Davis

A new study offers a beacon of hope for a cease-fire in the Golden State's persistent water wars.

"Floodplain Farm Fields Provide Novel Rearing Habitat for Chinook Salmon," published in the journal PLOS ONE, is based on the work by scientists from nonprofit group California Trout, UC Davis, and the California Department of Water Resources. The study provides further evidence that Central Valley farm fields that remain in active agricultural production can have environmental benefits for the state's salmon populations.

This surprising synergy runs counter to the usual California narrative where conflict over management of water and endangered species is the norm. This is particularly true in the State's Central Valley, where more than 95 percent of former wetlands—critical for populations—have been leveed, drained and developed, primarily for farmland.

Food for fish and people

"This study demonstrates that the farm fields that now occupy the floodplain can not only grow food for people during summer, but can also produce food resources and habitat for native fish like salmon in winter," said lead author Jacob Katz of California Trout. "Our work suggests that California does not always need to choose between its farms or its fish. Both can prosper if these new practices are put into effect, mimicking natural patterns on managed lands."

Approximately 10,000 small, hatchery-reared salmon, averaging less than 2 inches and weighing about a gram, were transplanted to a 5-acre for several weeks between the fall rice harvest and spring planting. A subsample of the fish were tagged uniquely with electronic tags (similar to chips used to ID pets) to allow tracking of individual growth rates, which were among the highest ever recorded in freshwater in California.

Floodplain farm fields benefit juvenile salmon
Juvenile salmon. Credit: Carson Jeffres/UC Davis

"By reconnecting rivers to floodplainlike habitat in strategic places around the Central Valley, we have the potential to help recover endangered salmon and other imperiled fish populations to self-sustaining levels," said Ted Sommer, lead scientist for the California Department of Water Resources and a co-author on the study.

Rice fields as floodplains

Since 2012, a team of scientists has been examining how use off-channel habitats, including off-season rice fields. The experiments provide evidence that rice fields managed as floodplains during winter can create "surrogate" wetland habitat for native fish.

The team suggests that shallowly flooded fields function in similar ways to natural floods that once spread across the floodplain, supplying extremely dense concentrations of zooplankton—an important food for juvenile salmon. Foraging on these abundant and nutritious invertebrates, the young salmon grow extremely quickly, improving their chances of surviving their migration to sea and returning in three to five years as the large, adult fish.

Since this original study, the team has continued to investigate how rice fields and other managed habitats could be improved to support rearing.

"This study shows that we can start focusing on solutions that support and people, instead of one or the other," added Carson Jeffres of the UC Davis Center for Watershed Sciences, the second author on the report. "It's a huge win-win."

Explore further: Report: California fish face extinction on increased level unless trends change

More information: Jacob V. E. Katz et al. Floodplain farm fields provide novel rearing habitat for Chinook salmon, PLOS ONE (2017). DOI: 10.1371/journal.pone.0177409

Related Stories

For fish and rice to thrive in Yolo Bypass, 'just add water'

October 24, 2013

From a fish-eye view, rice fields in California's Yolo Bypass provide an all-you-can-eat bug buffet for juvenile salmon seeking nourishment on their journey to the sea. That's according to a new report detailing the scientific ...

Scientists study under-appreciated fish with special tag

May 29, 2017

Most people think of salmon jumping upriver to spawn when they consider wild fish in the American Northwest. But another, lesser-known species—the Pacific Lamprey—is also culturally and historically important to the region. ...

How will salmon survive in a flooded future?

October 17, 2016

As torrential rain descends on the Pacific Northwest, new research published online in the journal Global Change Biology provides a glimpse of how salmon rivers might fare in a future with larger floods.

More bad news on California salmon

December 16, 2015

California drought regulators, deliberating on a controversial plan to withhold water from farms and cities next year to preserve an endangered species of salmon, were handed a fresh dose of bad news Tuesday: The fish are ...

Recommended for you

Re-cloning of first cloned dog deemed successful thus far

November 22, 2017

(Phys.org)—A team of researchers with Seoul National University, Michigan State University and the University of Illinois at Urbana-Champaign has re-cloned the first dog to be cloned. In their paper published in the journal ...

Testing the advantage of being left-handed in sports

November 22, 2017

(Phys.org)—Sports scientist Florian Loffing with the Institute of Sport Science, University of Oldenburg in Germany has conducted a study regarding the possibility of left-handed athletes having an advantage over their ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.