Feds May Look at Spring-Run Chinook Salmon as Genetically Distinct

(CN) --- The National Marine Fisheries Service is considering whether the spring-run and fall-run Chinook salmon that occupy the rivers of Northern California and southern Oregon are genetically distinct. 

The decision has huge implications for fish populations as the number of spring-run Chinook salmon has plunged to such depths it would almost certainly result in a listing under the Endangered Species Act if seen as a separate species. 

“The science is in on that,” said Rich Nawa, an ecologist who petitioned the agency a year ago to consider the spring-run Chinook salmon as genetically distinct. “There are several papers so no one disputes the science, it’s just how to incorporate it into policy at this point.”

The fisheries service said Monday it will consider the new science as it analyses whether an update to its listing policy is warranted.

“We find that the petition presents substantial scientific and commercial information indicating the petitioned action may be warranted,” the agency said in a document. 

The key word in the phrase is “may,” as a significant dispute exists in the scientific community whether the spring-run Chinook is what is referred to as an “evolutionarily significant unit.”

Researchers at the University of California, Santa Cruz published a study last fall that said both the spring-run and fall-run Chinook are genetically similar and that any differences are tantamount to small differences in humans, like height and eye color. 

“It’s like blue and brown eye color in humans — it just depends on what genotype you inherit from your parents,” said John Carlos Garza, a researcher with UC Santa Cruz and the National Oceanic and Atmospheric Administration. 

Other researchers say they have detected the genetic marker that separates spring-run Chinook from their fall-run counterparts. 

Spring-run Chinook behave differently, said Craig Tucker, a spokesman for the Karuk Tribe. For instance, spring-run chinook salmon enter the rivers of Northern California and southern Oregon during the spring runoff, when the rivers are swollen with snowmelt. The waters are cooler and historically the fish have used the higher water levels to reach places that fall-run Chinook salmon would be unable to after the rivers have shrunk to their post-summer levels. 

“They spend a lot of time in freshwater,” Tucker said. 

In fact, the fish spend the summer developing their reproductive organs before they spawn and die. Therefore the dams and reservoirs that have been installed at various points throughout the rivers of the West Coast create problems for spring-run Chinook that are unique and separate from their closely related cousins. 

It also allows the fall-run species to outcompete the spring run since they both are able to reach the same spots in the river to reproduce. 

It’s why Tucker thinks the dam removal on the Klamath River will help both salmon species immeasurably. 

Dam removal looks inevitable as federal agencies are finalizing the environmental analyses required to pave the way to remove four dams on the Klamath River as soon as 2023. 

“I am convinced it’s going to be a giant boon to fish in this basin,” Tucker said. 

But Nawa said a listing of the spring-run Chinook salmon will also allow the federal agency to formulate conservation and recovery solutions specific to the species.

“We have to keep the spring-run Chinook salmon as a functioning population in the future,” Nawa said. 

Chinook salmon are native to the northern Pacific Ocean and the river systems of western North America. They are anadromous fish, meaning they are born in freshwater, spend most of their lives in the ocean and then return to the freshwater systems of their birth to spawn and die. 

The fish is a major staple in the diets of North Americans and contains spiritual and cultural significance to the many Native American tribes throughout the western part of North America. 

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