Image Source: https://www.oregonlive.com/
A record-shattering number of coho has made the long journey from their home streams to the ocean and back.
Nearly 24,000 coho salmon have made passage through the Lower Granite Dam on the Snake River — the last dam between the ocean and the Grande Ronde and Wallowa rivers.
The prior record, set in 2014, saw 18,098 coho make their way past the Lower Granite Dam. In recent years, those numbers have fluctuated between 1,449 and 8,178, with 2020 seeing just 7,797 coho return to the Lower Granite Dam. The run this year marks a more than 300% increase from the previous year.
Part of that return could be attributed to the Nez Perce Tribe’s monumental work to reintroduce coho to the Clearwater Basin in the late 1990s, and recently in the Lostine River in 2017. The tribe’s efforts returned the salmon to the Lostine River after it was bereft of the silvery fish for more than 40 years.
Becky Johnson, production division director for the tribe’s Fishery Resource Management, was there when nearly 500,000 smolt were released into the Lostine River in 2017. She described the release as “awesome.” The results were almost immediate — the next year, two coho were caught in the tribe’s weir. Then, in 2021, 88 fish were caught in the net.
“Salmon are a really amazing, resilient creature, and if you just give them half a chance, if you provide the right conditions, the habitat and the clean water — I’ve been impressed with what they can do,” Johnson said.
To be sure, not every coho released into the Lostine would return — predation and harvesting take their toll, as do natural diseases and parasites. Many more would return to different streams to spawn, in a process called straying. Still, the return is more than welcomed, and their journey was a long one in both length and time.
“We have a lot of work, we’ve only just begun really, but I know from our experience from over here in the Clearwater that it can be really successful,” Johnson said.
Between 1980 and 1996, a total of only 89 coho salmon were counted at the Lower Granite Dam. Due to the reintroduction efforts, the fish have returned to the Snake River in higher numbers — though far removed from their previous numbers, before the construction of the eight dams between the Pacific Ocean and the confluence between the Clearwater River and the Snake River at Lewiston, Idaho.
“I want to put it in context, though,” Johnson said, “because you know coho used to be very abundant up here just like spring chinook and fall chinook and steelhead. Historically, there were probably about 200,000 coho that returned here (to the Lostine River). So we’re super excited — happy to see this return of coho this year, but also want to contextualize that this is a mere fraction of what it used to be like here.”
According to Johnson, the program to reintroduce coho to the Lostine is based on the tribe’s success in the Clearwater Basin. The tribe reintroduced the salmon to the Clearwater and Snake basin areas in the late 1990s. Before then, the fish were extinct in the area.
The fish were bred from stock collected at the Bonneville Dam. The next phase of the Lostine coho program will use returned fish as brood stock for the next generation of salmon, hoping to make use of the fish that made the long journey home.
“Those fish have survived,” Johnson said. “They’ve not only migrated out as juveniles for 600 or so miles over eight dams to the ocean, but then they also turned around and came back up those eight dams over those 600 miles, so we want to use those genetics, you know that stamina from those adults for the next generation. That’s what we did on the Clearwater, and it’s been pretty successful.”
At the same time as the record-breaking coho run, a smaller number of chinook and steelhead runs have made their way back up the rivers. Steelhead trout, especially, were returning in much lower numbers than before.
Just 39,359 steelhead have made it past the Lower Granite Dam this year, in contrast to its 10-year average of 59,147, according to the U.S. Army Corps of Engineers. The 2020 numbers for steelhead were 55,307, according to the same data.
But the reason for the coho’s greater numbers have flummoxed experts.
“Coho are bonkers all the way up the West Coast, and I don’t really know why to be honest,” said Kyle Bratcher, a fish biologist with the Oregon Department of Fish and Wildlife. “There’s something going on in the ocean that’s changed that’s allowed them to do well.”
The effects of the recent drought, as well, could play a part in the years to come, Bratcher said, though the effect will be muted by regional environmental factors and the current La Nina weather system.
It also will be some time before the impact of the drought can be accurately gauged, as the life cycle of chinook, coho and steelhead vary — steelhead and chinook can take up to six years to make a return, while coho’s much shorter lifespan of two to three years means that it can act as a bellwether for ocean and weather conditions.
“We get a little bit lucky sometimes because we have the Wallowa Mountains here, we tend to still keep a little cool water around even when it gets pretty bad,” Bratcher said. “We didn’t see any of that this year but where it’s going to hurt us — the drought — is probably in the next two or three years, especially in the return.”