Salmon and a Warming River

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WERC biological science technician Shannon Waters is part of a research team studying the effects of warming water temperatures on Chinook salmon. On Tuesday, April 3rd, she visited the California State University, Sacramento to talk to students and the interested public about the team's findings.

The many branches of the Yukon River bring water and other resources to much of the Alaskan landscape. One of those resources is the Yukon river Chinook salmon (Oncorhynchus tshawytscha). However, the number of Chinook salmon that complete their yearly migration to freshwater spawning grounds has declined rapidly since the late 1990’s. The consequences have rippled throughout local fisheries and economies, and affected those who rely on subsistence fishing.

Thousands of miles south in Davis, CA, Shannon Waters is part of a team examining a possible link between warming temperatures in the Yukon River and falling numbers of Chinook salmon. Together with the USGS Alaska Science Center and the U.S. Fish and Wildlife Service (USFWS), WERC ecologist Dr. Lizabeth Bowen and Waters are using sensitive molecular technologies to determine how Chinook salmon respond while under thermal stress.

Photo of USGS biological science tech Shannon Waters holding a salmon for release

USGS biological science technician Shannon Waters releases a Chinook Salmon into an Alaskan river. (Public domain.)

A Chinook salmon begins life as a tiny egg in a freshwater stream or river. Once it hatches, it travels downstream through the Yukon River, growing strong on crustaceans, and terrestrial and aquatic insects until it reaches the open sea. It spends on average 3-4 years in the open sea, and when it’s time to spawn, the fish must make the arduous journey back to the river or stream where it hatched, a migration, for some, as long as 2,000 miles. However, increasing water temperatures in the Yukon may be negatively affecting successful spawning.

In July 2017, Waters traveled to the Yukon River to sample wild Chinook salmon making their final migration upstream. She and colleague Randy Brown from USFWS took biopsy samples from salmon caught on a fish wheel rotating close to the river’s shore. The samples were shipped back to Davis, where Waters searched for indications of an increase in heat shock proteins.

Waters shared her preliminary findings with undergraduates and the interested public at the California State University, Sacramento during the spring 2018 Sacramento State-USGS Colloquium Series. Audience members asked Waters detailed questions — How did a salmon’s experience at sea affect its chances of survival on its upstream migration? Was it possible to look at how heat stress affected salmon across generations? In the future, these ambitious questions could lead to insights into the many variables influencing salmon survival.

This coming summer Waters will return to Alaska to assist with conducting a thermal stress experiment on Yukon river Chinook salmon and to further analyze the link between rising water temperatures and the species’ decline. Results from this study can help resource managers and fisheries maintain healthy local Chinook salmon populations, especially during warm years. Learn more at the project webpage.

Chinook Salmon Data

Data collected on Chinook salmon caught in the Yukon River. (Public domain.)

Shannon Waters Lifting Chinook Salmon

USGS biological science technician Shannon Waters lifts a Chinook salmon out of a fish wheel in the Yukon River, AK. (Public domain.)