Habitat & Species
Aquatic habitat and species in the Great Slave sub-basin are undergoing moderate change. Unhealthy fish with physical deformities and softer flesh and mass fish die-offs have been observed by many Indigenous communities. Populations of some fish species are declining, such as grayling (Thymallus arcticus) and suckers (Catostomus spp.) in the Mackenzie River, and inconnu (coney; Stenodus leucichthys) stocks near Yellowknife. Mercury and arsenic contamination affect fish populations in certain waterbodies near historical mine sites; however, in most places scientific data show that fish are safe to eat. Indigenous communities have reported new fish species rarely or never seen in the sub-basin, such as inconnu (coney) near Lutselk’e and salmon near Yellowknife. Documented scientific or Indigenous Knowledge observations of changes in wetland cover and riparian forests in the sub-basin are limited. However, some Indigenous communities have observed changes in wetland-dependent animal populations, particularly more variability in beaver (Castor canadensis) populations and a continued decline in muskrat (Ondatra zibethicus) abundance.
The following table summarizes the availability of information for each Habitat and Species indicator.
Signs and Signals
Indigenous Knowledge Information and Data
Indigenous Knowledge Availability1
Science Information and Data
Science Data Availability2
Oral histories and local observations of fish abundance, timing and distribution, species diversity and fish health condition. Local observations about changes in timing of local fishing activity and yield.
Many observations from several locations.
Fish (including salmon, suckers, pickerels, burbot) abundance, timing and distribution, species diversity and fish health condition.
Oral histories and stories of wetland and forest (and other habitat / land use) Local observations and oral histories of number, location and total area of wetlands
Some observations from few locations.
Number, location and total area of wetlands. Species diversity in wetlands where available.
Limited information on wetland cover and no information on change over time.
Local observations and oral histories of riparian forests
No information found.
Number, location, total area of riparian forests areas. Species diversity of riparian forests where available.
Data only available for Alberta portion of Slave River watershed.
1Qualifiers for the availability of local and Indigenous Knowledge observations in publicly available sources: Limited = 1-2 observations; Some = 3-4 observations; Many = 5 or more observations
2 Qualifiers for the availability of science data in publicly available sources: Low = Individual studies or locations; Many = Network of monitoring stations across the basin
Declines in fish populations and fish health condition have been observed by Indigenous communities in some areas in the Great Slave sub-basin. Contaminant levels in fish are safe for consumption according to scientific data, except in specific water bodies that are affected by historical mining impacts.
Akaitcho fishers also report a decline in coney stocks around Yellowknife, in areas where they used to fish. Declines in stocks of grayling (Thymallus thymallus) and suckers have been noted by members of the Dehcho First Nations, particularly in the Mackenzie River. A recent study showed a 70% decrease in Number of fish Per Unit Effort (NPUE: individuals/1000 m2/net set) and Biomass Per Unit Effort (BPUE: Kg/1000 m2/net set) over time in several areas of Great Slave Lake, which may point to a decline in fish populations.
The commercial fishery in the Northwest Territories is relatively small: ca. 1000 t/yr for the entire territory and Great Slave Lake accounts for roughly 90% of that. Significant commercial fishing on Great Slave Lake began in the mid-20th century but annual production has been in decline since the 1960s due to overharvesting and dwindling fish harvester participation. By the 1960s, lake trout (Salvelinus namaycush) harvest had collapsed due to overexploitation. Initially, lake trout was the main focus, although lake whitefish was also harvested. The lake trout population is currently still being managed through catch limits. There was no indication of a decline in lake whitefish stock status among management areas. However, information gaps and uncertainties in the assessment were identified. Inconnu had also declined as bycatch of whitefish harvest and as of 2012 was assessed as being in the “Critical Zone” of the Precautionary Approach model framework based on CPUE of mature female Inconnu. This means that the fish stock has been severely reduced, that stock management is focused on conservation and recovery and that fish harvest is limited to an absolute minimum.
Wetlands & Riparian Forests
Riparian areas in the Alberta portion of the Slave River watershed are intact, but information on the remainder of the sub-basin as well as changes over time in wetlands and riparian forests in the Great Slave sub-basin is limited. Indigenous communities have observed changes in wetland-dependent wildlife species, including beaver and muskrat.
Health & Wellbeing