Orleans, Calif. August 17, 2017 – This week a team of researchers at the University of California, Davis led by Dr. Michael Miller, published a report in the journal Science Advances that may have sweeping ramifications for salmon fisheries management all along the west coast and Alaska. The report describes the genetic difference between Chinook (or King) salmon that migrate into rivers in the spring versus the fall. The research provides new insights into salmon evolution and reveals that spring Chinook salmon deserve to be treated as its own evolutionarily distinct unit separate from fall Chinook. Before the age of dams, industrial mining, and clear-cut logging, spring Chinook salmon were the most abundant run of salmon in many Pacific Northwest Rivers. Today these fish are nearly extinct throughout much of its historic range.
Already, the report has led the Karuk Tribe to start the process necessary to have spring Chinook in the Klamath River added to the Endangered Species List. The Klamath River flows from southeastern Oregon to California’s north coast and is one of three rivers that power the West Coast commercial salmon fleet. Klamath spring Chinook were specifically used in Miller’s study.
Spring Chinook enter rivers in the spring when snow melt swells rivers allowing the fish travel into the upper reaches of a watershed. Then they must reside in cold water areas all summer until they spawn and die in the fall. Fall Chinook migrate into rivers in the fall where they spawn and die relatively soon after entering fresh water. “Having two life strategies allow Chinook to take advantage of the entire watershed instead of just the upper or lower reaches,” explains Toz Soto, Senior Fisheries Biologist for the Karuk Tribe. “This behavioral diversity enhances the chances of long term survival for the entire population.”
“Dams are the single greatest threat to Spring Chinook,” explains Karuk Councilman Josh Saxon. “Dams prevent Springers from accessing the upper reaches of watersheds where the cold water habitat they need to survive the summer is located.”
Miller and his colleagues’ research rewrites our understanding of Chinook salmon’s evolutionary history. “By using new advances in molecular biology, they quickly compared hundreds of thousands of DNA segments of one individual salmon to hundreds of others. This allowed them to locate a very small region of DNA that is always different between spring and fall Chinook,” explains Craig Tucker, Ph.D., Policy Advocate for the Karuk Tribe. “Miller’s research shows that the difference between spring and fall run Chinook is a small change in a single gene. This change has occurred only once in Chinook’s evolutionary history which means that if we lose spring Chinook, we can’t expect them to re-appear for millions of years.”
Miller’s findings contrast with the previously held notion that salmon populations evolved the spring run behavior many times over across watersheds. If that were true, it would mean that the spring run behavior is relatively easily for Chinook to develop. In the past, federal agencies have declined to add spring Chinook to the Endangered Species List for this very reason. “This new finding will force agencies to reconsider their stance on spring Chinook in the Klamath and many other watersheds,” says Saxon.
The genetic difference between spring and fall Chinook is in a gene called Greb1L which has been shown to play a role in fat metabolism. This makes sense to Saxon. “We can taste the difference. Springers have a long way to swim before reaching their spawning grounds so they enter the river full of body fat which is why they taste so good.” Spring Chinook typically have 30% more body fat than fall Chinook.
The population of Chinook salmon that swims up the Klamath River in the spring once numbered in the hundreds of thousands. In a recent survey, divers at the Salmon River Cooperative Spring Chinook and Summer Steelhead Population Snorkel Survey only found 110 Spring-run Chinook, which is the second lowest return in over 20 years since the counts started.
“We have known all along that fall Chinook and spring Chinook, or ishyaȃt, are a distinct species,” says Karuk Natural Resources Director Leaf Hillman. “It’s about time western science catches up to traditional wisdom since that’s what is needed to make the policy changes necessary to save this part of our culture.”
Spring Chinook advocates currently have January 2020 circulated on their calendars. That’s when the removal of the lower four Klamath River dams is slated to begin pursuant to an historic agreement between dam owner PacifiCorp, California, Oregon, Tribes, and conservation groups. The project would be the largest salmon restoration project in US history. For spring Chinook and the Karuk Tribe, it can’t come soon enough.