Canada: A phenomenon known as "winterkill" is blamed for fish deaths in Banff National Park

Winterkill at Vermilion Lakes. (Parks Canada) | Image credits: ctv

Parks Canada says the death of thousands of fish in Vermilion Lake near Banff is due to a phenomenon known as "winterkill."

The government group said it was called on January 7 after large numbers of dead or dying fish were found in the lake.

According to officials, the fish died from extremely low dissolved oxygen levels, a naturally occurring condition known as "winterkill."

Bitter winters occur when the snow or ice above the water's surface becomes thick enough to prevent light from entering the water. Without sunlight, aquatic plants and algae cannot produce oxygen through photosynthesis.

Winterkill at Vermilion Lakes has killed thousands of fish, some of which were then eaten by birds. (Parks Canada) | image credits: ctv

Parks Canada said the reduction in the amount of oxygen available to aquatic life under the ice would lead to "mass fish die-offs."

Winterkill most often affects shallow, nutrient-rich lakes and wetlands.

"Larger lakes hold more oxygen and are more resilient to winterkill," Parks Canada explained.

The two fish species affected are the white sucker and brook stickleback.

"Both of these species are common in Canada and are not species at risk," Parks Canada said.

"These species are also good at colonizing new environments. Therefore, it is likely that Vermilion Lakes will be colonized by the same species from the surrounding waters that weren’t affected by winterkill.

"We do not expect this event to lead to a decline of these species in the region."

Parks Canada says it will monitor Vermilion Lake and consider other interventions as needed.

Banff National Park experienced at least two recorded winter kills at Vermilion Lake in 1959 and 1964, the group said.

If you see a wildlife in distress or that has died, please report it to Parks Canada at 403-762-1470.

source: ctv