Just keep swimming may be the motto juvenile steelhead and salmon are practicing with their return to the White Salmon River.
Six years after the removal of the Condit Hydroelectric Project, the U.S. Geological Survey (USGS) is monitoring the return of migrant juvenile salmon and steelhead to the White Salmon River. Continuing efforts from 2016, fish biologists collaborating with the Mid-Columbia Fisheries Enhancement Group have been successfully monitoring recolonizing populations of juveniles by utilizing screw traps and electrofishing.
According to the Mid-Columbia Fisheries Enhancement Group, work on the White Salmon River is part of a broader assessment studying the recolonization of the White Salmon River by salmon and steelhead after the removal of the Condit Dam.
Last Wednesday, USGS fish biologists visited the White Salmon River screw trap site (located at river mile 1.4 near the “White Salmon ponds,” which are old fish-rearing raceways) to record data from captured juveniles and to release new catches upstream.
The screw trap is a large floating metal platform with a rotating mesh component, which filters out juvenile fish as they swim downstream. The trap then stores juveniles in a holding tank until they’re collected by biologists.
By catching juvenile fish in the screw trap, surveyors can sample a population of steelhead and salmon leaving the river and create a data set to compare to future fish populations.
The trap was placed in the White Salmon at the end of March, and will be checked routinely until its planned removal sometime in June.
“This is the second year for actually seeing what’s coming out of the river,” explained USGS fish biologist Jill Hardiman.
“We know a little bit about what’s going on with the adults,” Hardiman added. “We know there’s a lot of Chinook reds that occurred downstream of here, and that there are some Chinook reds occurring upstream of here. We know there are some steelhead getting in to tributaries and spawning, but before we started doing our juvenile monitoring work we didn’t know what was coming out.”
The 2017 juvenile monitoring study is being funded by the Washington State Salmon Recovery Funding Board and the Clark-Skamania Flyfishers.
“Before the dam was removed, there was The White Salmon Technical Working group that met and came up with a strategy to just let things naturally occur for at least five years after the dam was removed before any sort of management decisions would be made about what’s going on with the fish,” explained Hardiman.
“There’s been ongoing monitoring work happening, but this is only the second year for juvenile monitoring work,” said Hardiman.
“It’s really cool that this year we’re catching so many Chinook fry, because last year we just didn’t know if it had just been that flood or just the spawning upstream that wasn’t successful,” USGS fish biologist Ian Jezorek added.
“We know that Coho are successfully also spawning in tributaries up above this site. As of this year, we are getting quite a few Chinook fry. So, we know that Chinook are also successfully spawning and producing juveniles up above this site, and the steelhead as well,” said Hardiman. “We’ve been getting steelhead from last year and this year.”
Since the dam’s removal U.S. Fish and Wildlife Services, as well as Washington State Department of Fish and Wildlife, have been conducting Chinook spawner surveys on a yearly basis, “all the way up to above Husum Falls. Then, Yakama Nation is doing steelhead spawner surveys, mainly in the tributaries not in the mainstem,” she explained.
Hardiman and Jezorek will check the screw trap six days a week until it’s removed this summer. Each check entails Hardiman and Jezorek removing the screw trap’s catch of the day, and transferring the catch to a cooler.
Juvenile fish are then netted one at a time, placed in a mild anesthetic to relax them, measured, weighed, clipped for a DNA sample, and if they’re large enough, a Passive Integrated Transponder (PIT) is injected for future monitoring.
“Yesterday [May 23] we had 53 fish, mostly fry,” said Jezorek. “We don’t catch all the fish going by. There’s a lot of river out there and that’s a little trap. So, we take the fish that we capture, and we mark them.”
When a fish is too small for a PIT tag, another more visible approach is taken. Instead of a tag, small fish are placed in a dye, known as a Bismarck Brown Solution, which tints their fins for a week and allows for easy recognition if recaptured in the screw trap.
“Fish that we tag, either through PIT tags or dying, we take them upstream about a kilometer, release them, and the assumption is they’re going to come back by and we’ll recapture a certain percentage of them,” explained Jezorek.
“If we release 100 fish upstream that we tagged or marked and catch 10 percent of them within the next week, then we know our total number of fish that we caught. With that we generate the population estimate,” said Jezorek, adding that he’d be happy if their recapture rate was 10%.
“Last year we were around 5 percent on steelhead and Coho smolts, which is not too bad. This year will be a bit lower,” he noted, “but we have gotten some recaptures, so we will be able to make an estimate.”
Last year’s data have yet to be released, and this year’s survey is still being processed, so an official data comparison can’t be made yet.
“Every year is different. We’re just at year two, we can’t give you a trend or anything, but that’s why we’re doing this work to see what all is coming back in, try to get a handle on the number of fish that are going out,” explained Hardiman. “And it is distribution in a sense that we’re seeing everything from this site to up above.”