5 per cent.
That’s what’s left of the once-thriving population of cutthroat trout in Alberta. Combine that with a 70 per cent loss of habitat for Alberta’s provincial fish, the bull trout, and things aren’t looking too positive for our freshwater fishes. Both cutthroat and bull trout are now restricted to high elevations, when they were once abundant through the Oldman and Bow river basins.
Facing multiple pressures
So why the dramatic decline? The biggest threat might not be what you think: off-highway vehicles. Quads, 4x4s, dirt bikes, and other off-highway vehicles tear up the stream bottom, compromise important habitat, and increase the amount of silt and sediment being deposited into important spawning grounds.1
But it’s not just our off-roading friends to blame. The creation of logging roads, expansion of energy development, effluent runoff from feedlots, and draining of watersheds to meet irrigation needs are all part of the problem. Together, these pressures create an ecosystem that is heavily disturbed, and its estimated that the disturbance density of the Oldman watershed are ten times the recommended maximum to ensure the long-term health of cutthroat and bull trout.
But why is silt and sediment a problem?
We used to think silt and sediment would just be washed away when it entered our waterways, but this actually isn’t the case: these tiny particles of sand and dirt become trapped in the bigger stones and gravel that make up the stream bed, where it solidifies. Eventually, the sediment and silt becomes so concentrated in the seafloor that water can’t permeate through it, creating what is referred to as a “hardpack streambed.” This makes it extremely difficult for trout to carve out redds (nests) – and hardpacks aren’t expected to go anywhere soon.
Echoed all over the province
In order to see real, lasting change for all of our native species of fishes and freshwater species, Alberta will need to address its land-use policies and make considerable changes.2 Some of these would include better protection for headwaters, more control of industrial activity, and improved water quality monitoring.
What can you do?
The biggest thing we can do to ensure the long-term health of our freshwater species is to limit the impact we have on our waterways directly. When you’re out camping, leave some distance between your site and the water. Don’t use your off-highway vehicle in or near the water. And make sure you use caution down on the waterfront.
CBC News. (June 13, 2015). Alberta trout threatened, say anglers and environmentalists. Retrieved from: http://www.cbc.ca/news/canada/calgary/alberta-trout-threatened-say-anglers-and-environmentalists-1.3112452.
Bob Weber. (July 12, 2015). Most Alberta trout streams threatened: survey. The Canadian Press. Retrieved from: http://globalnews.ca/news/2106366/most-alberta-trout-streams-threatened-survey/.