Distribution
In the Moose River Basin, lake sturgeon are found throughout many of the larger rivers and their tributaries in the northern Lowlands and the central Clay Belt. They are mostly absent from the more southern Canadian Shield portions of the basin (Figure 4). Natural barriers such as waterfalls, as well as man-made dams, limit the range of lake sturgeon in parts of the basin. Currently, 15 dams are located on large rivers within the traditional range of lake sturgeon. In some of these rivers, the range of lake sturgeon has been reduced by 30 per cent or more.
Figure 4. Current distribution and condition of lake sturgeon populations in the Moose River Basin.
Abundance
With some localized exceptions, lake sturgeon populations in the Moose River Basin and its large rivers (Moose, Mattagami, Abitibi, and Groundhog rivers) contain moderate numbers of fish. The Little Long Generating Station reservoir and its tributaries in the northern section of the Mattagami River support a population of roughly 12,400 adult fish. This is the largest number of adult lake sturgeon in any known population in northeastern Ontario. The closeness of spawning, nursery, and feeding habitats contribute to the high number of lake sturgeon at this location.
In the southern and mid-sections of the Abitibi River, including Lake Abitibi, lake sturgeon are either scarce or no longer present. Similar trends are seen in the Mattagami River between Timmins and Smooth Rock Falls (at Highway 11). The portion of the Frederick House River from Frederick House Lake north to the Abitibi River supports a relatively small, self-sustaining lake sturgeon population. Portions of the Groundhog and Mattagami rivers north of Highway 11 support relatively robust populations of lake sturgeon. There is limited access to these areas and little development has occurred. Spruce Falls in the town of Kapuskasing marks the southern limit of lake sturgeon in the Kapuskasing River. In the Missinaibi River, lake sturgeon are only found north of Thunder House Falls. The falls are a natural barrier to lake sturgeon movement. This population has yet to be assessed. The population in the Moose River (Figure 5) between Moose River Crossing and Moosonee/Moose Factory is representative of a harvested fishery.
Overall, lake sturgeon populations in the Moose River Basin tend to be average or moderately strong relative to other parts of Ontario. Southern Ontario and the Great Lakes drainage basin tend to have smaller populations due to over-harvesting in the late 1800s and subsequent habitat loss from river developments and pollution. Sturgeon populations in northwestern Ontario are similar to those in the Moose River Basin. Populations in the Winnipeg and English river systems are the exception. They have low numbers of fish. Most lake sturgeon populations in Ontario’s far north have not been assessed. Remote sections of rivers probably support larger populations of lake sturgeon than sections closer to human settlements.
Figure 5. The Moose River near Moose River Crossing.
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