Fall brings brown trout spawning time along Calgary’s Bow and Elbow rivers, and a group of citizen scientists hope to capture a better picture of how that fish population is faring.
Volunteers with Calgary River Valleys (CRV) were on the Bow River from Baker Park to Parkdale counting spawning nests called redds.
“It’s been exciting to see redds. I didn’t know they existed before today,” said volunteer Karen McPherson who was on her first redd count on Sunday. “I didn’t know what they were called. It was great to be able to point them out and see so many of them today.”
It’s fairly easy to spot redds: they stand out as lighter sections of the bottom.
Once a female has found her redd, she will clear it of debris and silt. The eggs need to be protected and need to receive adequate amounts of oxygen.
Trout Unlimited has been doing a redd survey on Calgary’s south end of the Bow River and CRV has counted redds in the Elbow River for many years, but this is the first time they’ve been surveying north and central sections of the Bow.
“We’ve been doing the side channels and one that we did had a large number of redds,” said retired fisheries biologist Chris Bjornson, who also volunteers with CRV.
The citizen scientists are finding the redds are more concentrated this year.
Jordan Pinkster with Trout Unlimited said areas where they saw redds in previous years wouldn’t support anything this year with how low the water is. That’s forcing fish into much tighter areas.
The Bow River in Calgary is currently flowing at 38 cubic meters per second. Normal for this year time of year should be high 40s and up to 65 cubic meters per second.
The province issued fishing restrictions this summer because the water was too warm and the water levels too low.
Brown trout are more adaptive than other trout in warm water, but the warmer river water this summer is not a friend to fish.
“Really high water temperature reduces the amount of oxygen,” Bjornson said.
The Alberta angling restrictions took effect in late July and continued to mid August.
The ban covered all rivers and streams in the Eastern Slopes Fisheries Management Zone 1, which goes from Calgary west to the mountain parks and south to the U.S. border.
The fishing restrictions were due to water temperatures and flows reaching certain thresholds.
The thresholds that have been set to protect fish are:
- when average daily water temperatures exceed 20 C or three or more consecutive days and
- when flows in the Bow River are below the 25th water flow percentile for 4 or more days at that time of year, as measured at the Carseland monitoring station.
The spawn is the most stressful time in a trout’s life, so it’s important to be mindful of where you or your dog steps during the spawning season. Stepping on a redd can mean the end of hundreds of eggs.
CRV has been collaborating with other groups to count Brown Trout redds in the lower Elbow River since 1994. This year’s count begins Friday.
CRV said the annual count helps to ensure the data collected is accurate, that trends over time can be observed and the location of redds can be used to ensure land use decisions don’t negatively impact Calgary’s trout fishery.
The Brown Trout Redd Count project is supported by funding from City of Calgary Water Services.
Comments