Forty-five percent of California's native salmon, steelhead and trout species face extinction within 50 years, and nearly three-quarters will be wiped out in a century without intervention, a study released yesterday said.
The analysis from California Trout (CalTrout) and University of California, Davis, Center for Watershed Sciences blamed climate change as a primary culprit, titling the report "State of the Salmonids II: Fish in Hot Water." It details the status of 32 types of salmon, steelhead and trout native to the Golden State.
"Climate change is and will have wide-ranging effects on California salmonids across the state," said Patrick Samuel, conservation program coordinator at CalTrout, a fish and watershed advocacy group. "Climate change is reducing the amount of cold water available to our fishes, which is critical to their survival. Climate change alters the volume and timing of stream flows, can degrade habitats and alter food resources for our species."
Salmon, steelhead and trout all depend on cold water for survival, the report said.
"Climate change is the overarching threat to our cold-water salmonids," Samuel added.
California's historic drought — which Gov. Jerry Brown (D) recently declared over — hurt many fish, the report authors said.
"The drought here is not over for these fish" due to a time lag in the species' life cycles, said Rob Lusardi, one of the UC Davis authors.
The findings are important not just for those who love fish or going fishing, said Curtis Knight, CalTrout executive director. It's not an answer to simply farm fish if freshwater varieties die off, he said. Freshwater fish are a kind of canary in the coal mine for water.
"Their health and their resilience indicates healthy waters, which is important for all Californians' drinking water, agriculture, commerce, and the health of the people and the environment in which we live," he said during a call with reporters. "The decline of the fish indicates the decline of all of our water. That's important to all Californians."
The report will be used to urge lawmakers and others to make changes that can help the fish.
"This report should rightly be considered an alarm bell, but it should also be seen as a road map for how we can correct course to better support native aquatic species," said study co-author Peter Moyle. "Thanks to ongoing scientific research, we now know what to do — and where — to improve the plight of native fish."
One in particular that could counteract a climate impact is restoring meadows, Knight said. More precipitation is expected to come as rain rather than snow in the future. That means the snow in the state's Sierra Nevada will fall farther north in the state. The snowpack traditionally has provided water as it melts in the spring and summer.
"Meadows, they can also act as those sponges, act as those reservoirs to slowly release water, but a lot of them are degrading" particularly at the 5,000- to 8,000-foot level, Knight said. "In the face of climate change it's going to be important to restore those" so that they can "capture rain runoff to store that and slowly release it."
The report is an update of one in 2008. The revision is needed because in part "the impacts of climate change have become more clear," said Moyle, associate director of the Center for Watershed Sciences. "We have a lot more information than we did 10 years ago."
Many native fish already are in trouble, Samuel said. The majority of salmon and steelhead are in a state of critical concern, he said. A total of 81 percent saw an increase in the level of concern since 2008.
Climate affects fish food
Fish under the most urgent threat include central California coast coho salmon, Sacramento River winter-run chinook salmon, southern steelhead, Kern River rainbow trout and McCloud River redband trout.
The report detailed what it calls key threats to the survival of each species, starting with climate change. In addition to the change in water temperature, climate alters food for the fish, the report said.
"In the Pacific Ocean, climate change is likely to reduce the powerful upwelling of the California Current, which drives primary productivity and supports the entire food web for all marine life, including anadromous fishes," it said. "Increased ocean acidification is also likely to impact ocean productivity."
Rising sea levels also play a role as they "are likely to inundate and degrade important estuarine and lagoon habitats, historically critical components of the juvenile salmon and steelhead life cycle," the report said.
The analysis also highlighted various other man-made threats to the fishes including changes in estuaries, dams that block access to traditional spawning habitats, agricultural practices, urbanization, and transportation.
Knight said the marijuana industry, which is now legal in the state, has created an "exploding" impact on land and water. All types of agriculture demand water, the report said. That reduces and alters the timing of stream flows and degrades water quality and habitat. During the drought, tension existed over keeping cold water in rivers and streams for fish versus pumping it for agriculture and urban use.
The Westlands Water District, a large trade group for farmers in California, did not immediately respond to a request for comment.
The report recommended other changes that included protecting the most productive river ecosystems in California, such as the Smith and Eel rivers.
"These strongholds, among others, have the capacity to support diversity and abundance because they retain high-quality habitat and are not heavily influenced by hatcheries, supporting the persistence of wild fish," CalTrout and UC Davis said.
Keeping more water in streams will reduce stress on fish during drought, buffering the effects of climate change, they said. Sierra Nevada meadow restoration, springs protection and progressive groundwater management all contribute to this effort, they added.
Restoring function to once-productive but now highly altered habitats also is needed, they said. That "can greatly improve rearing conditions for juvenile fish, especially floodplains, coastal lagoons, estuaries and spring-fed rivers."
Other options include altering landscapes to mimic natural processes, they said. CalTrout said it has shown that offseason farmland can be used to replace traditional floodplains and support rapid growth of juvenile salmon.
The state should prioritize improving fish passage to historical spawning and rearing grounds that have been cut off over time, they said.
"We know we are not going to turn back the clock to a time before rivers were dammed or otherwise altered for human benefit," Knight said. "Using the best available science, we can make landscape-level changes that will allow both people and fish to thrive in California."
Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.