Tuesday, October 14, 2014
The Transcanada Pipeline crosses the South Saskatchewan River 8.2 km upstream of here. I settle on a view of castle-like formations directly across the river and perch my folding chair on a low grassy bank just back from the cobbly shore, near a seepage that leaves the pebbles crusty with alkali. Fred explores a bar of cobbles just to
my right that is littered with heavy thick shells of Fat Mucket (Lampsilis radiata siliquoidea) astonishingly more abundant than we'd seen on the Red Deer River.
After I'd set up to paint he walks back to the campground, planning to explore the shore along the row of campsites, but finding the bank a little too steep and crowded with willows to see much. After a while the band of willows becomes narrower and he finds a path down to the shore. Even this narrow shore is dotted with big heavy pairs of Mucket shells. He picks up about 8 pairs in an area where fishermen had been scaling fish, and then climbs up the slope to the bridge, finding crayfish-filled Raccoon scats, a Rattlesnake skin, and Great Horned Owl, bones - then scuttles along a narrow provision for pedestrian passage across the bridge, to the other side. There he admires a Western Grebe swimming and diving in midstream and proceeds along a steep bank of Sandbar Willow, past a Beaver drag-track, to a gravel bar which is littered with big Lampsilis shells of all ages. These are piled the deepest right at the upstream end of the bar - white drifts of huge shells!
On his way back to me, Fred meets the lady who manages the campground, and is told that Sturgeons swallow the clams, digest their soft parts, and leave the shells unbroken. She says that a lot of the Sturgeon here are enormous. As it is all across Canada, the huge, cartilaginous, bony-plated, sucker-mouthed Lake Sturgeon is classified as a Species At Risk, and populations are much lower than they used to be. The take by angling in the South Saskatchewan River is restricted to one. However, if predation by Sturgeon really is the cause of the mortality of these big heavy-shelled Lampsilis, that may be why on the whole 3 hectare gravel bar, Fred found only one Lasmigona complanata (White Heel-splitter) and none of the thinner-shelled Pyganodon (Floaters). Either they don't occur here or the Sturgeon crunch them up completely.