Fish levels studied in wake of flooding
High water levels kept anglers in Central Alberta on the sidelines early in the season and garnered mixed results once they did cast their fishing lines.
David Christiansen, fish and wildlife manager for the Clearwater area with Alberta Environment and Sustainable Resource Development, said fishing success has varied depending on the water system.
One angler he spoke to said brown trout were biting on the Red Deer River below Dickson Dam, while a few others were concerned there were fewer fish at Blackstone River and Wapiabi Creek north of Nordegg.
Government staff still have to analyze data they collected recently on the upper Red Deer River in the Sundre area.
“Their sense was maybe young of the year for mountain white fish was lower this year, which would be consistent with what we’d see after a significant flood event,” Christiansen said on Tuesday.
“It’s early days. We’ll be getting reports from anglers and continuing with the field work we have yet to do this year and see what that tells us.
“We annually have a high runoff event. Our fish in our streams are adapted to putting up with a certain amount of flooding. But when you get these real extreme events, that’s when it can maybe go outside the range of tolerance and can expect to have some impact on the populations.”
But Central Alberta should not see the reduction in fish that Southern Alberta will likely experience after severe flooding stranded some fish once water receded, he said.
“At higher flows we often get higher suspended sediment levels, so there can be some direct mortality because of that. The soil in the water can actually abrade the fish’s gills and cause some physical damage. It can also cover the substrate and kill the smaller fish in the substrate.”
Upper systems in the western area may have had some cutthroat trout eggs still in the gravel when flooding occurred, he said.
“There could have been some loss of eggs and fry.”
Problems at Central Alberta lakes were not found nor were they expected, he said.
“They might have had more inflow, but the conditions in the lakes wouldn’t have changed that much. It’s mainly a stream fish situation that we’re concerned about.”
A voluntary catch and release program has been in place in Central Alberta on flowing waters west of the forestry trunk road that crosses Hwy 11 at Nordegg. Catch and release is more extensive in Southern Alberta.
“When we’re uncertain about the magnitude of the impact, erring a bit on the side of caution seems like the reasonable thing to do.”
Sam Livingston Fish Hatchery, which was hit by Bow River flooding, is operating below capacity so Raven Brood Trout Station near Caroline is switching gears to focus on trout rearing instead of just egg production to build fish stock for next year.
Christiansen said Central Alberta didn’t see a significant decrease in adult fish populations after the 2005 flood. But there were some changes in the composition of fish communities.
“Flooding is a natural occurrence. In as much as bed load movement and movement of gravel can impact eggs in the stream bed, it can also help to clean the stream bed. It can actually clean sediment that accumulated over the years when we didn’t have much flooding. We had reports of that happening after the 2005 in some areas in Southern Alberta.”
Much like a fire can rejuvenate a forest, flooding can also improve aquatic systems, he said.