Out of the Ice: The North Saskatchewan's Glacier Source

Like a finger of frosting dripping from the top of an iced cake, the Saskatchewan Glacier drains from the "Snow Dome" of the Columbia Icefields, one of the world's largest non-polar accumulations of ice and snow. The Columbia ice cap, covering a high plateau between Mount Columbia and Mount Athabasca in the Canadian Rocky Mountains, is a remnant of a vast ice sheet that stretched from the foothills of the Rockies to the Pacific Coast 15,000 years ago. With an area of almost 325 square kilometres, and a depth of 365 metres, it is the largest ice formation in a chain of icefields that runs along the Great Divide between the provinces of Alberta and British Columbia. The Icefield has been advancing and retreating for thousands of years; while its last advance occurred as recently as the early 1800's, during the climatic period known as the "Little Ice Age," Columbia's glaciers are currently receding.

Three-Way Flow: The Saskatchewan glacier is one of 6 major glaciers, or ice lobes, fed by the Columbia Icefields. Meltwater from its "snout" forms the headwaters of the North Saskatchewan River, which joins the Saskatchewan and Nelson Rivers to flow into Hudson Bay, and ultimately, to the Atlantic Ocean. Glacial waters from the Columbia ice cap also flow to the Arctic Ocean via the Sunwapta, Athabasca, Slave and Mackenzie Rivers and to the Pacific Ocean via the Creek, Bush and Columbia Rivers. The Snow Dome of the Columbia Icefields is known as the "hydrographic apex" of North America, because it is the only point on the entire continent from which rivers drain into 3 oceans.

Outlet Valley Glacier: The Saskatchewan Glacier, which can be seen from the Saskatchewan Valley Viewpoint in Banff National Park, is the longest tongue of ice flowing from the Columbia Icefields. It is a classic example of an "outlet valley glacier," a glacier which drains an inland ice cap and flows via gravity through an existing gap in surrounding mountains.

Sustaining Saskatchewan River Sturgeon

There's a lot riding on a few middle-aged female lake sturgeon in the turbid waters of the North Saskatchewan River. With a total population of less than 2,000 fish, of which only about 200 are mature (capable of spawning), about 100 are female and only about 25 actually reproducing in any given year, the survival of an entire species is dependent on the reproductive efforts of a perilously small number of fish.

Alberta lake sturgeon are a unique species consisting of only 2 populations divided between the North Saskatchewan and South Saskatchewan Rivers. They exist at the westernmost limit of North America's lake sturgeon range. Most populations are found in the central regions of the continent. Although there are far fewer sturgeon today than there were a century ago - largely due to commercial over-fishing early in the 20th century - the St. Lawrence River currently maintains a relatively stable population, and Quebec numbers remain robust enough to support a modest commercial fishery. (In the United States, the state of Wisconsin has one of the largest self-sustaining lake sturgeon populations in the world. Wisconsin's fisheries management goal of 156 sturgeon per kilometre is 62 times greater than the North Saskatchewan's current density of 2.5 fish per kilometre!)

Saskatchewan River sturgeon populations are still reeling from the impact of heavy gill net and long line commercial harvesting prior to 1940. A fishing closure from 1940 to 1968 helped populations to recover enough to support a carefully regulated sport fishery. Recent studies, however, indicate that, given an apparent mortality rate of 10% - 20% (a combination of legal harvest, poaching and natural mortality) numbers of mature fish in both the North and South branches may still be too low to guarantee long-term sustainability.

Sustainability Factors: Biologists have determined that a critical density of senior sturgeon - seemingly geriatric 50 - 80 year-olds - is needed to maintain a viable population. Achieving that density is an ongoing challenge, and is dependent on both external environmental conditions, and the unique biological characteristics of the fish itself:

• Lake sturgeon need a highly varied habitat in order to complete their lengthy life cycle. When spawning, they require fast-flowing water to scatter their eggs, and a rocky river-bottom to receive and protect them. As juveniles, the fish need flat, sandy bottoms, and as adults, they seek deep, slow-moving pools with a combination of silt and rock. They also need room to roam, especially at spawning time, when they undertake migrations of up to 500 kilometres. In the past century, damming of both the North and South Saskatchewan Rivers has altered both the flow and composition of the riparian environment, interfered with natural spawning triggers, limited movement of the sturgeon, and created barriers that have isolated the river's populations.

• Lake sturgeon are voracious and highly opportunistic feeders, using their sensory whiskers or "barbels" and their suction-like mouth to move along the river-bottom like insatiable aquatic vacuum cleaners. They eat everything from mayflies to mollusks, larvae to leeches, plants, fish and fish eggs, and require massive amounts of food in order to grow to attain the 10 -14 kilogram weight, 130 centimetre length and 15 -30 year age that triggers reproductive capability. Dam outflows, which tend to warm the river during the winter and cool it during the summer, can cause depletion of aquatic species that are sensitive to temperature fluctuations. As the sturgeon's density of prey is reduced, the growth rates of sturgeon are also reduced, and the number of mature, reproducing fish falls to a dangerously low level.

• Water diversion and pollution can also cause a reduction in prey and result in limits to sturgeon growth. Hydroelectric dams, storage reservoirs for irrigation and discharge of industrial, municipal and domestic effluents all have a negative impact on aquatic populations. Furthermore, studies have shown that juvenile sturgeon are particularly sensitive to chemical pollution, and the extreme longevity of the species raises concerns about bioaccumulation of toxic contaminants. Recent improvements in disinfection and nutrient reduction of City of Edmonton discharges have resulted in reduced bacteria and phosphorus levels in the North Saskatchewan River.

• Even in ideal conditions lake sturgeon populations are naturally susceptible to decline. They are by nature a slow-growing, late-maturing, infrequently-reproducing species. The first 15 -25 years of a male sturgeon's life, and 20-30 years of a female's, are devoted to growing big and strong. Sexual maturity is delayed in both sexes, and females that have reached reproductive age spawn only about every 4 - 6 years. If the population suffers other stresses, as it has in the North and South Saskatchewan Rivers, it is unable to rebound quickly, and may remain depleted for decades.

Planned Protection: In response to the critically low levels of reproduction-age sturgeon in the Saskatchewan River, the Alberta government has developed a Lake Sturgeon Management Plan. Sport catches in the slightly more populous South Saskatchewan River are limited to 1, with a minimum size of 130 centimetres. In the North Saskatchewan River, sport fishing is limited to catch-and-release only. Ongoing conservation efforts are designed to further reduce the sturgeon's current mortality rate to the lowest possible levels by restoring and maintaining optimal habitat and eliminating hooking mortality and illegal harvest.

Warm and Dry on the Kootenay Plains

As it heads east out of its source in the Rocky Mountains, on its way to Abraham Lake, the North Saskatchewan River flows briefly through an unusual area of arid terrain known as the Kootenay Plains. This dry, almost desert-like landscape is the result of a weather phenomenon known as a "rain shadow." A shadow occurs when a mountain range squeezes the moisture from the air flowing up its windward side, and sends the warmed, dried air down its leeward side:

• As warm air reaches a mountain range, it is lifted up the slope, cooling as it rises (in a process known as "orographic lifting.")
• The cooling of the air creates cloud formation, rainfall, and frequent thunderstorms on the windward slope.
• When the cooled air begins to descend the leeward side of the mountain, it is dry. As it moves down, it warms and expands, further reducing the possibility of precipitation.
• The shadow effect keeps the moist windward side of the mountain filled with vegetation, but causes the leeward side to be dry and barren.

The rain shadow effect on the Kootenay Plains results in an annual precipitation level of no more than 15 - 30 centimetres, less than half the average annual rainfall in the rest of Alberta. The area's dry, sunny microclimate is further enhanced by the moderating effect of Abraham Lake, the longest man-made lake in the province. Pleasant summer temperatures and above average winter temperatures create a benign, oasis-like ecosystem that attracts a wide variety of birds and wildlife and supports plant species found nowhere else in the North Saskatchewan watershed. Foraging ungulates, such as elk and deer, are drawn to the Plains in the winter, when low precipitation levels provide a welcome respite from the deep snows of surrounding terrains.

Hike or bike on the trails of the Kootenay Plains Ecological Reserve, an area that protects the grazing ranges of elk, bighorn sheep and mountain goats, and features 60 species of birds, 14 mammals and over 240 vascular plants. The Reserve is nestled between the ridges of Windy Point and Whirlpool Point on the David Thompson Highway (Highway 11) between Saskatchewan River Crossing and Nordegg. Bouns Video