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Posts Tagged: salmon

Flood protection, agriculture, fish and wildlife coexist in the Yolo Bypass

Egrets, herons and other birds feast in a wild rice field in the Yolo Bypass. (Photo by Trina Wood)
At times during the winter and early spring it looks like a vast inland sea between Sacramento and Davis. This is the Yolo Bypass, which shunts Sacramento River floodwater around the state capital during high flows. You drive over the bypass on a three-mile-long elevated stretch of Interstate 80 known as “the Causeway” (the Blecher-Freeman Memorial Causeway). The bypass is also the site of a lot of innovative fish and wildlife work.

From late fall through winter you can see thousands of ducks, geese and other waterfowl winging over the bypass’s flooded rice fields and the restored wetlands in the Vic Fazio Yolo Basin Wildlife Area. 

Black-crowned Night-Heron. (Photo by Trina Wood)
The Central Valley of California is one of the nation’s most important migratory waterfowl corridors. The bypass provides essential winter habitat for these birds on their annual migration. The wildlife area is managed by the California Department of Fish and Wildlife. Learn more.

A recent article in The Sacramento Bee featured a research project at a rice farming area in the upper reaches of the bypass that is examining how flooded fields could be used to fatten up young salmon during a crucial time in their life cycle. One part of the study is examining how soil type influences the production of insects — an important source of food for growing salmon. Carson Jeffres, a fish ecologist with the UC Davis Center for Watershed Sciences, is quoted in the story: "There are hundreds, if not thousands, of insects that are coming out of each 9-by-6-inch block of earth." You can also watch a YouTube video to hear UC Davis doctoral student Jacob Katz describe the project and read more about why fish find this floodplain so attractive in a previous Green Blog post by writer and photographer Trina Wood.

Part of the wildlife area is accessible by automobile — when it’s not flooded! Consider taking a tour of this remarkable and easily accessible area, or take binoculars to view the many birds. UC Davis fisheries professor Peter Moyle prepared a guide that will help you make the most of your visit.

Posted on Wednesday, February 27, 2013 at 7:13 AM

Wine and fish for dinner? Water management required

The competition between farmers and fish for precious water in California is intensifying in wine country, say biologists at the University of California, Berkeley.

Juvenile steelhead trout, shown here in a small stream pool, are hit hard when water levels are low. (Ted Grantham photo)
A recently published study links higher death rates for threatened juvenile steelhead trout with low water levels in the summer and the amount of vineyard acreage upstream. Like salmon, steelhead trout migrate from freshwater streams to the ocean before returning to their birthplace to spawn. Steelhead trout in Southern California and the upper Columbia River are endangered, and several other populations, including those in Northern California, are threatened.

The researchers found that juvenile steelhead trout are particularly at risk during the dry summer season typical of California’s Mediterranean climate. Of the juvenile steelhead trout present in June, on average only 30 percent survived to the late summer. In years with higher rainfall and in watersheds with less vineyard land use, the survival of juvenile trout over the summer was significantly higher.

The researchers pointed out that salmon and trout conservation efforts have not adequately addressed summer stream flow. Previous studies have highlighted other limiting factors such as habitat degradation and water quality, while this study documented the importance of water quantity for restoring threatened populations.

Aerial view of vineyard agriculture in Sonoma County. Vineyards that divert water from streams used by juvenile salmon and steelhead trout could reduce their impacts by storing winter rainfall in small ponds such as the ones seen in this photo. (Adina Merenlender photo)
“Nearly all of California’s salmon and trout populations are on the path to extinction and if we’re going to bring these fish back to healthy levels, we have to change the way we manage our water,” said lead author Theodore Grantham, a recent Ph.D. graduate from UC Berkeley’s Department of Environmental Science, Policy and Management (ESPM). “Water withdrawals for agricultural uses can reduce or eliminate the limited amount of habitat available to sustain these cold-water fish through the summer.

Grantham says he is not suggesting we get rid of vineyards. “But we do need to focus our attention on water management strategies that reduce summer water use. I believe we can protect flows for fish and still have our glass of wine.”

Posted on Friday, May 18, 2012 at 10:20 AM

Bleak future for spring-run Chinook salmon

Spring-run Chinook salmon, photographed in Butte Creek (Allen Harthorn/Friends of Butte Creek)
Warming streams could spell the end of spring-run Chinook salmon in California by the end of the century, according to a study by scientists at UC Davis, the Stockholm Environment Institute (SEI) and the National Center for Atmospheric Research (NCAR).

There are options for managing water resources to protect the salmon runs, although they would impact hydroelectric power generation, said UC Cooperative Extension associate specialist Lisa Thompson, director of the Center for Aquatic Biology and Aquaculture at UC Davis. A paper describing the study was published online recently in the Journal of Water Resources Planning and Management.

“There are things that we can do so that we have the water we need and also have something left for the fish,” Thompson said.

Working with Marisa Escobar and David Purkey at SEI’s Davis office, Thompson and colleagues at UC Davis used a model of the Butte Creek watershed, taking into account the dams and hydropower installations along the river, combined with a model of the salmon population, to test the effect of different water management strategies on the fish. They fed in scenarios for climate change out to 2099 from models developed by David Yates at NCAR in Boulder, Colo.

In almost all scenarios, the fish died out because streams became too warm for adults to survive the summer to spawn in the fall.

The only option that preserved salmon populations, at least for a few decades, was to reduce diversions for hydropower generation at the warmest time of the year.

“If we leave the water in the stream at key times of the year, the stream stays cooler and fish can make it through to the fall,” Thompson said.

Summer, of course, is also peak season for energy demand in California. But Thompson noted that it might be possible to generate more power upstream while holding water for salmon at other locations.

Hydropower is often part of renewable energy portfolios designed to reduce greenhouse gas emissions, Purkey said, but it can complicate efforts to adapt water management regimes to a warming world. Yet it need not be all-or-nothing, he said.

“The goal should be to identify regulatory regimes which meet ecosystem objectives with minimal impact on hydropower production,” he said. “The kind of work we did in Butte Creek is essential to seeking these outcomes.”

There are also other options that are yet to be fully tested, Thompson said, such as storing cold water upstream and dumping it into the river during a heat wave. That would both help fish and create a surge of hydropower.

Salmon are already under stress from multiple causes, including pollution, and introduced predators and competitors, Thompson said. Even if those problems were solved, temperature alone would finish off the salmon — but that problem can be fixed, she said.

“I swim with these fish, they’re magnificent,” Thompson said. “We don’t want to give up on them.”

Other co-authors of the paper are graduate student Christopher Mosser and Professor Peter Moyle, both in the Department of Wildlife, Fish and Conservation Biology at UC Davis. The study was funded by the U.S. Environmental Protection Agency.

Posted on Friday, September 16, 2011 at 11:17 AM
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