Hooray for Floodplains, Food Webs and Fish!


This excellent video describes the Nigiri Project at Knaggs Ranch in the Yolo Bypass. Watch as these students explain the importance of floodplains to producing food for salmon fry. These young fish move from the gravel spawning beds on the Sacramento and Feather Rivers toward the ocean. Due to our flood control levees they have lost 95% of their floodplain feeding grounds.

Lulu the Wonder Dog sniffing out the fish at Knaggs Ranch.

Lulu the Wonder Dog sniffing out the fish at Knaggs Ranch.

Farmers in the Yolo Bypass have been working with UC Davis and government scientists to prove that fish will grow at record rates on rice fields when flooded in the winter time. As the fields are drained, the fish continue their journey to the ocean and the food is flushed into the Delta where it provides food for Smelt and other native fish.

Local stakeholders have worked out an integrated plan that meets flood, fish, farm and waterfowl needs. It is now before government agencies to seize the opportunity for breakthrough.


Nigiri Project: salmon on rice

The Yolo Bypass is tucked between Woodland and Sacramento and yet when you are in the middle of it you feel a million miles away.  My car stirred great blue herons and snowy white egrets as I drove along the levee to meet John Brennan and Emily James.  I had forgotten just how great is the wingspan of these birds so I slowed and paid attention to their elegant flight.

John and Emily directed me to park my car and I hopped into their truck. Our first stop was at the top of the property where they operate a  seasonal earthen dam to direct water from the Ridge Cut Canal at the bottom of the Colusa Drain into the fields. This is the water that floods up the rice fields in winter to decompose rice stubble and provide waterfowl habitat. With duck season over at the end of January,most rice farmers or duck club managers have pulled out the boards on the fields and drained them. They’ll go on vacation with their duck club widows and then return to begin prepping the fields for planting rice in April.

There are other crops grown in the Bypass–safflower, sunflowers, tomatoes–and cattle and sheep graze, but in this section the predominance of clay soils makes it good for growing rice.  And there is a long established symbiosis between waterfowl and rice.   What seems like a new idea is that this seasonal floodplain might also be ideal for fish.

In 2001 Ted Sommers and colleagues published a paper about the importance of floodplains as temporary Chinook salmon habitat.  It caused some excitement at the time, but it took just over 10 years before he was able to stage an experiment with hatchery salmon fry in the Yolo Bypass.

Before the levees, when the salmon runs were much higher than today’s 50,000 fish, the young salmon would regularly find themselves out on the various floodplains that bordered the Sacramento River where they were  able to find a safe place to feed and grow before heading out to sea.

This year the seasonal floodplain was recreated on the lower five acres of a Yolo Bypass rice field. Ted’s crew with the Department of Water Resources (DWR) and a crew from UC Davis set up experiments with 10,000 hatchery fish: releasing them to eat and grow from the end of January to mid-March.

Recently I was able to visit the intentional floodplain to see the conclusion of the experiment.  The two crews worked together to catch and count the fish before they released them into the Bay Delta.

A portion of the fish had microchips inserted that made it possible to wand them and record their growth rates. The DWR study is straightforward: fish in, fish out, fish size and fish health.Their preliminary findings showed very healthy fish that had doubled in length and quadrupled in size.  The UC Davis study designed by Peter Moyle and Jacob Katz prepared various rice stubble treatments and made fish pens within the floodplain to hold fish and see if their growth and survival rates varied with the various treatments. These are the black pens in the midst of the flooded field.

The UC Davis grad students were also taking random samples of fish to measure and a few were packed to take back to the lab to check for other growth indicators.

On the day I visited the mood was jubilant.  Everyone was working to count the fish before the forecasted storm made it harder to get into the site.  They were also having a good time doing what they love most.

John Brennan the farm manager for the Cal Marsh & Farm Ventures where this project is taking place is one of the most enthusiastic and well-spoken of the team members.  He has spent hours explaining the project to reporters and others who need to understand what the potential is for fish in the Yolo Bypass.

John can envision a wayto manage for fish on the their rice fields on a seasonal basis. And he explains how this 5 acre project can be incrementally expanded until 1,000,000 small salmon safely grow to a size where they have a better shot at making it to adulthood.  If they can improve the return rate of the fish to 2% , then this site can potentially grow the salmon run from 50,000 to over 70,000 and so on.

John thinks the project is important because it stresses the integrated management of a working landscape, which he sees as the path forward, with the agricultural community, as the true stewards of the land, taking a lead role in the designing and implementing the environmental solutions of the next generation.

It is also an important lynchpin in the conservation strategy for managing the water supply operations in the Delta under the current Biological Opinion (that is the opinion by the fish agency NMFS about what steps must be taken to keep the salmon from becoming extinct). It becomes even more important in the proposed Bay Delta Conservation Plan.

The idea is controversial.  Yet, the Yolo Basin has long had multiple uses as farmers and wildlife refuge managers have worked together to provide flood protection, food, and habitat.  This is another benefit that can be accommodated if good will can prevail.