A dry winter destroys California’s salmon and trout population

A severely dry winter temporarily but dramatically changed the range of three fish in North California waterways – Chinook salmon, salmon and steel trout.

In a new study published this week in the Journal Proceedings of the National Academy of SciencesBiologists found that the unusually dry winter of 2013-2014 caused salmon and steel heads to temporarily disappear from individual tributaries, even the entire watershed along the Northern California coast.

“California is at the southern end of several species of salmon and trout, which have been weakened due to the impacts from colonization and engineering controls on western rivers to climate change.” “Our findings provide a glimpse of how a single extreme event triggers widespread and sudden collapse of multiple populations and species and can lead to long-term scope changes.”

During California’s historic multi-year drought in 2012-2016, there was little rainfall in the winter of 2013-2014 and the rainy season started very late. By late January 2014 and early February 2014, when the first heavy rainstorms arrived, many of Northern California’s streams and rivers were very low, and in some people, their mouths were completely dry, preventing salmon and Steelhead’s annual voyage, thus making their annual voyage to spawning.

The study examines how drought affects Chinook salmon, Coho salmon and Steelhead Trout, a genus called the “Salmon” in 13 coastal watersheds, from Marin to Humboldt County. Although all three species of fish are affected, Chinook salmon can cope by diverting its breeding activities downstream. However, fish monitoring data in summer 2014 showed that Steelhead trout had been eliminated from many separate tributaries, while Coho Salmon had completely disappeared from three coastal watersheds.

“The timing of the river flow does not match the arrival of the fish because of the delay in rainfall, and we see different effects on different species in different places,” Carlson said. “The most extreme case is Coho salmon spawning in coastal rivers that form an intermittent estuary along the estuary during the dry season. During the dry season, the estuary along the estuary is formed. There are three systems in Mendocino, Sandbar never opens for a full year, and Coho Salmon is lost from the entire water.”

In the decade since that drought, all three species have completely returned to their original range. This is due to the life cycle diversity in fish populations and is also a protected hatchery in the Russian river. The salmon and steelheads spent years at sea before returning to breed at home and differently. Therefore, during the 2013-2014 season, some of the fish in the affected rivers were still growing at sea and were able to return in the second year to help reoccupate these rivers.

“This complexity in the population is really important to enable them to prevent annual changes in the climate, including against extreme events,” Carlson said. “This emphasizes the importance of diversity in the population and the need to prioritize restoration of the historical diversity of life among the population to restore resilience.”

Tracking the “missing queue” of salmon

The study began in the summer of 2014 when Carlson graduate students Suzanne Rhoades and Cleo Woelfle-Hazard were investigating two different field sites along the California coast. Rhoades confusingly observed that she lacked juvenile iron-headed trout at a research site in the southern fork of the Eel River. Meanwhile, Woelfle-Hazard found that his research site in the Salmon Creek Basin in Sonoma County was also missing Coho salmon.

“I thought, ‘Well, it’s really unusual,” Carlson said.

Carlson began to contact colleagues to see if other basins were missing salmon. She soon established a connection with Mariska Obedzinski, a graduate student in environmental science, policy and management at UC Berkeley, who all observed similar disturbing patterns in Russian river systems.

“At that time, I began to understand that this could be a pretty common event,” Carlson said. “We saw teenagers disappear, but also observed adults that were produced in unusual times or unusual places. We quickly realized that something happened that limited the ability of adults to enter their breeding grounds.”

Through speeches and word of mouth at the conference, Carlson continued to connect with other scientists who documented the mysterious salmon population. The final paper combines datasets from UC Berkeley, California Fish and Wildlife (CDFW), California High Grant and Martell Salmon Group’s Carlson Group. Carlson said large-scale analytics are facilitated because all organizations have adopted CDFW’s standardized protocol to collect fish survey data.

“This partnership between resource managers and academia is very important for salmon recovery,” Obedzinski said. “Without these long-term monitoring efforts across the state, we would never be able to understand the impact of these hydrogenation climate events on salmon populations.”

This detailed monitoring data will also be key to understanding how salmon and hard avatars adapt to the warm world and what enables them to persist in the face of increasing climates.

“Understanding the behavioral and life historic mechanisms that keep some salmons on the southern edge of their range, as they enable them to survive and adapt to conditions that will develop further under climate change,” said Mary Power, senior author of the study. “These characteristics may be key to salmon’s survival over most of the range on the warm earth.”

Other co-authors of the study include Kasey Pregler of UC Berkeley; Sean Gallagher of CDFW; Nathan Queener of Mattole Salmon Group; and Sally Thompson of University of Western Australia. This work was obtained by the National Science Foundation (CZP EAR-1331940, DGE 1752814 and 1106400), the United States Army Corps of Engineers, NOAA-Fisheries, CDFW (Q1996052), EEL CRITICY RIGHT RIGITER PISTRION VIRECTORATY PRIGTIAN POIRN VICERATOR and SOLANO COUNTY County Water Affairs Bureau.