Repost: https://www.skyhinews.com/news/cpw-surveys-fish-gears-up-for-movement-study-around-windy-gap/
For the fifth year in a row, Colorado Parks and Wildlife biologists, technicians and volunteers waded along the Colorado River with electrified poles and fishnets in hand.
The group followed a roughly 600-foot stretch of the Colorado River behind River Run RV Resort on Tuesday. The poles sent a field of electric current into the water, stunning the fish and making them easier to scoop up into nets.
Colorado Parks and Wildlife Aquatic Biologist Jon Ewert explained that since Granby purchased the section of river in 2016, CPW has been conducting fish population surveys for two spots on the Colorado.
There is a similar survey on the Fraser River. Trying to control for variability, the annual surveys occur at the same time each year.
While Ewert is interested in the fish population for any given year, the work also documents long-term trends.
“(A trend) really only becomes obvious once you’ve been doing it for several years and you have kind of a baseline data set established,” he said.
A CPW biologist collects captured fish along the Colorado River on Tuesday. Once all the fish along the 600-foot sample have been collected, the scientists collected population data and then implanted electronic tags for a separate study on fish movement.
Amy Golden/Sky-Hi News
Ewert does not have any reason to expect a major population difference this year, but he’s being extra vigilant following the East Troublesome Fire. He said that reach of the Colorado has been “off color” all year because the water coming through Willow Creek Reservoir has carried material from the burned area.
“One thing I will be watching for is, did we have less successful reproduction? Are there fewer juvenile fish?” Ewert said. “That’s the place I would expect to see that, is if there’s fewer juvenile fish as a result of the extra sediment in the water. I don’t know if that’ll be the case, but that’ll be one thing I’ll be looking closely at.”
Ewert added that he won’t know the results of this year’s population survey until he crunches the numbers later this year.
That’s not all the surveyors were doing Tuesday, though. After catching hundreds of fish and recording the data, the CPW scientists implanted each one with an electronic tag.
Separate from the population study, CPW is beginning work on a large-scale fish movement study for populations around the Windy Gap Reservoir in anticipation of the Colorado River Connectivity Channel.
The channel would loop around the reservoir and be capable of passing water, fish and sediment, thereby reconnecting miles of the Colorado and Fraser rivers, according to Northern Water.
Antennas have been installed in beds of rivers at different places, along with hundreds and hundreds of tags placed in the bodies of fish. The antennas will detect when fish pass, both before and after the planned Windy Gap bypass is installed.
The Windy Gap dam has been a barrier to fish movement since it was built in the 1980s. The bypass as envisioned will slightly shrink the size of the Windy Gap reservoir and allow for a river corridor to reconnect between the Colorado and Fraser rivers east of the reservoir and the Colorado River west of the reservoir.
The long-anticipated connectivity channel is expected to be built in the next few years.
“We’re very excited about the Colorado River Connectivity Project,” Ewert said. “We think it’s going to be a huge benefit to the ecological health of the Colorado River in Grand County. When you reconnect a habitat that’s been fragmented, that’s a huge benefit to all the critters that live in the river.”
The study will record fish movement all around the Windy Gap, establishing a baseline of patterns as they exist now to compare to the movement following the creation of the bypass.
“Hopefully what we’ll be documenting is a lot more fish movement,” Ewert said.
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