Tag Archives: drought

Survivor Salmon that Withstand Drought and Ocean Warming Provide a Lifeline for California Chinook

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October 28, 2021, fisheries.noaa.gov

NOAA Fisheries recovery goals include reintroduction to save the late-migrating fish.

A late-migrating spring run Chinook salmon from one of the few Northern California creeks that remain without dams. Credit: Jeremy Notch/UC Santa Cruz.

In drought years and when marine heat waves warm the Pacific Ocean, late-migrating juvenile spring-run Chinook salmon of California’s Central Valley are the ultimate survivors. They are among the few salmon that return to spawning rivers in those difficult years to keep their populations alive. This is according to results published today in Nature Climate Change.

The trouble is that this late-migrating behavior hangs on only in a few rivers where water temperatures remain cool enough for the fish to survive the summer. Today, this habitat is primarily found above barrier dams. Those fish that spend a year in their home streams as juveniles leave in the fall. They arrive in the ocean larger and more likely to survive their 1–3 years at sea.

Scientists examined the ear bones of salmon, called otoliths. These bones incorporate the distinctive isotope ratios of different Central Valley Rivers and the ocean as they grow sequential layers. They looked at Chinook salmon from two tributaries of the Sacramento River without dams that begin beneath Lassen Peak, north of Sacramento. Late-migrating juveniles from Mill Creek and Deer Creek returned from the ocean at much higher rates than more abundant juveniles that leave for the ocean earlier in the spring.

Scientists examined otoliths, the ear bones of salmon, to understand the migration timing of fish that survived drought and poor ocean conditions. Credit: George  Whitman and Kimberly Evans/UC Davis

The different timing characteristics of the fish are referred to as “life-history strategies.” Those with a late-migrating life history strategy represented only about 10 percent of outgoing juveniles sampled in fish monitoring traps. However, they were about 60 percent of the returning adult fish across all years, and more than 96 percent of adults from two of the driest years.

“Some years the late migrants were the only life-history strategy that was successful,” said Flora Cordoleani, lead author of the research and associate project scientist with NOAA Fisheries and UC Santa Cruz. “Those fish can make it through the difficult drought conditions on the landscape because they come from the few remaining rivers with accessible high-elevation habitats where water is cool enough through the summer.”

Recovery Strategies Include Reintroduction

The finding underscores the importance of providing secure cool-water habitat for fish so they can survive difficult conditions during drought and ocean warming, said Rachel Johnson, a NOAA Fisheries research scientist, UC Davis researcher and senior author of the study. “Most salmon blocked from their historical habitats appear to migrate just too early and perish once they encounter the warmer water temperatures during droughts.”

“It appears the late-migrating life history has evolved as an insurance policy against the unfavorable spring river conditions that occur during droughts,” said Corey Phillis, a researcher at the Metropolitan Water District of Southern California and co-author on the study.

The study also projected how Central Valley river temperatures would rise with climate change, leaving only a few higher-elevation rivers cool enough to still sustain salmon. Many of those areas are above existing dams without fish passage.

NOAA Fisheries has outlined reintroduction of salmon to cold-water rivers above dams as a critical recovery strategy for endangered Sacramento River winter-run Chinook, a NOAA Fisheries Species in the Spotlight. The reintroduction of threatened spring-run Chinook salmon to the San Joaquin River watershed has taken hold. Offspring of reintroduced spring-run Chinook salmon are now returning from the ocean. NOAA Fisheries is also advancing the reintroduction of spring-run Chinook to the upper Yuba River upstream of Englebright Dam.

The study found that temperatures would remain cool enough for salmon to survive in the north Yuba River as the climate changes.

“We need to reconnect salmon to their historical habitats so they can draw from their own climate-adapted bag of tricks to persist in a warming world,” Johnson said.

By growing for a year in their home river, the later-migrating fish head for the ocean bigger than the others and in cooler temperatures. That way, more survive and return to rivers to spawn when marine heatwaves warm the ocean and depress salmon survival. A Marine Heatwave Tracker developed by the Southwest Fisheries Science Center shows that heatwaves have become an increasing presence in the Pacific Ocean in the last decade.

A returning adult spring run Chinook salmon leaps from the water in California’s Central Valley. Credit: Carson Jeffres/UC Davis

Heatwaves Reduce Survival

A large heatwave currently stretching across the Pacific off Northern California and Oregon, as shown by the tracker, may affect salmon survival. Warmer ocean waters are generally less productive, reducing salmon survival and depressing returns to rivers.

NOAA Fisheries’ Northwest Fisheries Science Center has developed a “stoplight chart” that projects survival of different salmon species based on different factors at play in the ocean.

The researchers highlighted the importance of protecting varied life histories that may help their species survive climate change. This is particularly true in California, which is at the southern end of the range of many salmon and at the edge of conditions where they can survive.

“The rarest behaviors observed today may be the most important in our future climate,” said Anna Sturrock of the University of Essex and a co-author of the research.

“We show for the first time that the late-migrating strategy is the life-support for these populations during the current period of extreme warming,” the scientists concluded. “As environmental conditions continue to shift rapidly with climate change, maximizing habitat options across the landscape to enhance adaptive capacity and support climate-resilient behaviours may be crucial to prevent extinction.”

Researchers included:

  • NOAA Fisheries’ Southwest Fisheries Science Center
  • UC Santa Cruz
  • UC Davis
  • University of Essex
  • Metropolitan Water District of Southern California
  • Mediterranean Institute of Oceanography
  • Lawrence Livermore National Laboratory

More Information

Read original story on “Survivor Salmon” and explore more on NOAA Fisheries

 

Let’s Look at Past Successes to Encourage the Vision of a Brighter Environmental Future

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Too often the tone of environmental discourse —Crisis! Dire failure!—promotes hopelessness and paralysis. Brock Bernstein, President of the National Fisheries Conservation Center (Global Ocean Health is a program of NFCC), takes a different view. He was recently asked to write a blog entry for the journal Integrated Environmental Assessment and Management, and we think it’s an important message.

By Dr. Brock B. Bernstein

Pervasive doom and gloom dominates much of the popular news about the environment. Global warming, sea level rise, ocean acidification, drought, wildfires, overfishing, or overpopulation—it all contributes to a feeling of despair and hopelessness, particularly among young people. This struck home for me on a personal level during a recent conversation with my college-aged son and a few of his friends—they felt they were “totally screwed” because of the inevitable impacts of climate change.

Cuyahoga River fire, 1952. Courtesy clevelandmemory.org

One value of getting older is that you’ve seen more and have a longer history to draw on. I grew up in southern California from the 1950s through the 1970s when environmental problems were severe and visible – air pollution (I remember frequent episodes of eye-burning smog that caused incessant coughing fits during water polo practice) and sewage contamination that led much of Santa Monica Bay’s beaches to be permanently closed to swimming (1,2). While I was in graduate school, I visited a colleague in Cleveland in the late 1960s, just a couple of years after the Cuyahoga River caught on fire again, because it was so polluted that, as Time Magazine put it, the river “oozes rather than flows” (Time, August 1, 1969).

Los Angeles smog

Smog over Los Angeles basin. Credit: Al Pavangkanan, CC BY 2.0.

And yet, we’ve solved many of these and other problems that seemed so overwhelming at the time, and we’ve made major progress on newer ones such as the ozone hole. One useful thing about getting older is that it provides some protection against the shifting baseline phenomenon in which our perceptions are dominated by more recent information while the past recedes in our collective memory and is not part of our current awareness. For good reason, environmental advocates typically focus on shifting baselines that cause us to see current, degraded conditions as normal. For example, the average size of top-of-the-food chain fish, such as swordfish, has declined substantially since the 1800s (3), to the extent that most people cannot even imagine a 400-pound swordfish. Yet shifting baselines also diminish our awareness of past successes and the effort that went into them. My son and his friends were only vaguely aware of southern California’s decades-long battle against air and water (2) pollution. As a result, they have no experience of hard-won success to draw on as they consider what their future holds. And because they’re not in the engineering facilities and meeting rooms where solutions to California’s current extreme drought and likely drier future are being crafted and implemented, they—and much of the rest of the public—don’t appreciate the stunning speed with which solutions such as stormwater capture and the potable reuse of treated wastewater are being developed and implemented.

Read more here

National Climate Assessment Released

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May 6th, 2014, National Climate Report Overview

Climate change, once considered an issue for a distant future, has moved firmly into the present. Corn producers in Iowa, oyster growers in Washington State, and maple syrup producers in Vermont are all observing climate-related changes that are outside of recent experience. So, too, are coastal planners in Florida, water managers in the arid Southwest, city dwellers from Phoenix to New York, and Native Peoples on tribal lands from Louisiana to Alaska. This National Climate Assessment concludes that the evidence of human-induced climate change continues to strengthen and that impacts are increasing across the country.

Americans are noticing changes all around them. Summers are longer and hotter, and extended periods of unusual heat last longer than any living American has ever experienced. Winters are generally shorter and warmer. Rain comes in heavier downpours. People are seeing changes in the length and severity of seasonal allergies, the plant varieties that thrive in their gardens, and the kinds of birds they see in any particular month in their neighborhoods.

Other changes are even more dramatic. Residents of some coastal cities see their streets flood more regularly during storms and high tides. Inland cities near large rivers also experience more flooding, especially in the Midwest and Northeast. Insurance rates are rising in some vulnerable locations, and insurance is no longer available in others. Hotter and drier weather and earlier snow melt mean that wildfires in the West start earlier in the spring, last later into the fall, and burn more acreage. In Arctic Alaska, the summer sea ice that once protected the coasts has receded, and autumn storms now cause more erosion, threatening many communities with relocation.

Scientists who study climate change confirm that these observations are consistent with significant changes in Earth’s climatic trends. Long-term, independent records from weather stations, satellites, ocean buoys, tide gauges, and many other data sources all confirm that our nation, like the rest of the world, is warming. Precipitation patterns are changing, sea level is rising, the oceans are becoming more acidic, and the frequency and intensity of some extreme weather events are increasing. Many lines of independent evidence demonstrate that the rapid warming of the past half-century is due primarily to human activities.

The observed warming and other climatic changes are triggering wide-ranging impacts in every region of our country and throughout our economy. Some of these changes can be beneficial over the short run, such as a longer growing season in some regions and a longer shipping season on the Great Lakes. But many more are detrimental, largely because our society and its infrastructure were designed for the climate that we have had, not the rapidly changing climate we now have and can expect in the future. In addition, climate change does not occur in isolation. Rather, it is superimposed on other stresses, which combine to create new challenges.

This National Climate Assessment collects, integrates, and assesses observations and research from around the country, helping us to see what is actually happening and understand what it means for our lives, our livelihoods, and our future. The report includes analyses of impacts on seven sectors – human health, water, energy, transportation, agriculture, forests, and ecosystems – and the interactions among sectors at the national level. The report also assesses key impacts on all U.S. regions: Northeast, Southeast and Caribbean, Midwest, Great Plains, Southwest, Northwest, Alaska, Hawai’i and Pacific Islands, as well as the country’s coastal areas, oceans, and marine resources.

Over recent decades, climate science has advanced significantly. Increased scrutiny has led to increased certainty that we are now seeing impacts associated with human-induced climate change. With each passing year, the accumulating evidence further expands our understanding and extends the record of observed trends in temperature, precipitation, sea level, ice mass, and many other variables recorded by a variety of measuring systems and analyzed by independent research groups from around the world. It is notable that as these data records have grown longer and climate models have become more comprehensive, earlier predictions have largely been confirmed. The only real surprises have been that some changes, such as sea level rise and Arctic sea ice decline, have outpaced earlier projections.

What is new over the last decade is that we know with increasing certainty that climate change is happening now. While scientists continue to refine projections of the future, observations unequivocally show that climate is changing and that the warming of the past 50 years is primarily due to human-induced emissions of heat-trapping gases. These emissions come mainly from burning coal, oil, and gas, with additional contributions from forest clearing and some agricultural practices.

Global climate is projected to continue to change over this century and beyond, but there is still time to act to limit the amount of change and the extent of damaging impacts.

This report documents the changes already observed and those projected for the future.

It is important that these findings and response options be shared broadly to inform citizens and communities across our nation. Climate change presents a major challenge for society. This report advances our understanding of that challenge and the need for the American people to prepare for and respond to its far-reaching implications.

Read the full report here