Species Habitat

Habitat & Species

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Water Quality

Aquatic habitat and species within the Mackenzie Great Bear sub-basin are undergoing moderate change. However, this assessment is primarily based on observations of changes in fish populations, health and fishing practices reported by Indigenous communities. Fish are considered key species for supporting ecosystems and remain a core part of local diets, livelihood and culture[41]. New species like salmon and char have been observed, and a surge in populations of predatory fish like northern pike (Esox lucius) is thought to be shifting the balance of predator to prey species. Stocks of lake trout (Salvelinus namaycush) and Rat River Dolly Varden char (Salvelinus malma) have previously shown signs of population decline, and some fishers report catching less burbot (Lota lota) than in the past.  However, more recent studies of lake trout in Great Bear Lake indicate improved stock status. Reports of less healthy and skinnier fish with “softer” flesh and irregularities like sores and lumps have been made. Mercury levels in the tissue of subsistence fish species like Walleye and burbot have been examined and advisories on fish consumption have been issued in some lakes. Communities across the sub-basin have expressed concern for the health and sustainability of fish populations and many have adapted their fishing practices. Some Sahtu and Dehcho communities consume less fish than in the past due to concerns for elevated mercury levels, and the Gwich’in use a larger net mesh to reduce catching smaller fish and assist in ongoing efforts to restore char populations. Although this assessment includes scientific data for some fish species, limited data was found for Arctic fish stocks. Indigenous Knowledge and scientific observations of changes in wetlands and riparian forests in the sub-basin were not found.

The following table summarizes the availability of information for each Habitat and Species indicator.

Signs and Signals

Indigenous Knowledge Information and Data

Indigenous Knowledge Availability in Public Sources1
Science Information and Data2
Science Data Availability2

Fish

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/

Lack of data on fish stocks.

Few fish health data.

Wetlands

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

Limited observations from few locations

Number, location and total area of wetlands. Species diversity in wetlands where available.

2020 Canadian Wetland Inventory was published but still requires ground validation.

Scientific information on muskrat and beaver populations was not gathered for this report.

Riparian Forests

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.

No data found

1 Qualifiers 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

Fish

Changes in fish populations and health condition have been observed in the Mackenzie Great Bear sub-basin.

Changes in the presence and abundance of some fish species have been noted in studies with Sahtu and Inuvialuit communities. For instance, salmon and char have been observed in recent years in the Sahtu and Mackenzie River Delta regions of the Northwest Territories, despite never being seen there in the past.[42] A surge in populations of northern pike (Esox lucius), a predatory species that is considered undesirable for consumption by the Inuvialuit, has recently been observed in the Mackenzie River Delta. This has caused concern among the Inuvialuit in the shifting balance of predator to prey species. Fishers have observed scars on preferred species like inconnu (Stenodus leucichthys), which may indicate attempted predation by northern pike.[43]

[M]any participants reported an abundance of northern pike, representing a concern for ecosystem balance,

Heredia Vazquez, 2019

Observations of declines in some fish stocks have been recorded in studies with Inuvialuit and Gwich’in communities. While inconnu (Stenodus leucicthys) populations appear stable, Inuvialuit fishers report catching fewer burbot and whitefish in the Mackenzie River Delta than in the past.[44] The Gwich’in identified declines in Rat River Dolly Varden char (Salvelinus malma) stocks in both the 1980s and in 2004 when a population decline occurred, both of which were primarily attributed to overharvesting and a former practice of setting nets across critical migration waterways. Great Bear Lake is known for trophy sport fishing for lake trout (Salvelinus namaycush) and Arctic grayling (Thymallus arcticus).[45] The current harvest is considered below the maximum sustainable yield.[46] Sampling conducted by the Department of Fisheries and Oceans Canada included the analysis of trout otoliths to determine the average age of fish collected in various areas of Great Bear Lake including Keith and McTavish Arm.  In more recent years (>2006) the average age of fish collected has increased which indicates improved stock status.[47]

In the last few decades, the population, and catch, have really declined. Even before the voluntary closure, many people did not harvest char,

Gwich’in Social and Cultural Institute, 2010

Changes in fish health condition, most notably skinnier fish and fish with softer flesh, have been noted in studies with Indigenous communities from the Mackenzie River Delta, Sahtu, and Dehcho regions.[48],[49] Observations of fish with discoloured and unhealthy stomachs and livers and external irregularities like sores and lumps have also been recorded, which are attributed by communities to warmer water temperatures and water contamination.[50],[51],[52]

Mercury levels in the tissues of some fish species vary widely across lakes in the Dehcho region, where some lakes have fish[53]. A collaborative team of First Nations and academic researchers studied ten remote lakes in the Dehcho region and found that mercury levels were best explained by chlorophyll-a (an indicator of lake algae abundance), whereas mercury in northern pike depended on lake catchment composition, water clarity, and fish ecology[54] Mercury levels in burbot in the Mackenzie River at Fort Good Hope from 1984 to 2018 has been reported, but levels still remain below Government of Canada’s recommended action level[55]. Consumption advisories are posted online by the Government of Northwest Territories and included Kelly Lake and Lac St. Therese in the Sahtu region and a number of lakes in the Dehcho region, as of December 2019.[56]

Walleye (Sander vitreus) is valued as a subsistence fish by Indigenous communities throughout the sub-basin. It is one of the species tested for mercury concentrations. Image source: Jerry “Woody” via Flickr Creative Commons (copyright-free).

Scientific data on most Arctic fish stocks are limited due to prohibitive costs and challenging logistics.[57],[58]

Boat on the shores of the Mackenzie River, Tulita NT. Image source: michael_swan via Flickr Creative Commons (copyright-free).

Wetlands & Riparian Forests

Current wetland mapping is available but information on changes over time in wetlands in the Mackenzie Great Bear sub-basin is limited. Indigenous communities have observed changes in wetland-dependent wildlife populations.

Some observations of population changes of wetland-dependent animal species, like beaver, have been recorded. For example, an increase in beaver activity has raised concern among the Inuvialuit. Inuvialuit community members have observed how an increase in beaver dams and lodges along key waterways leads to lower water levels and disrupts travel and access to fishing areas, and in some cases, the dams prevent fish passage into preferred fishing locations.[59] Conversely, Gwich’in elders have observed that increased beaver activity is not disrupting char movement or habitat on the Rat River, but question why beaver activity is increasing.[60] Additional information on local observations of changes in wetlands was not found.

An increase in beaver activity has been observed in the northern portion of the sub-basin. Image credit: Becky Matsubara via Flickr Creative Commons (copyright-free).

Wetlands are a major component of the landscape in the Mackenzie Great Bear sub-basin, with percent coverage varying from 25% to more than 50%, depending on the ecoregion.[61] The Mackenzie River Delta located in the north of the sub-basin is the second largest wetland in Canada and supports a diverse array of wildlife, fish and birds.[62] Limited information was found on the changes in the total number and location of wetland areas and species diversity. A Canadian Wetland inventory completed recently indicates more wetland cover than that estimated by land cover mapping cited above, especially in the Plains around Mackenzie River and west of Great Bear Lake, but this inventory is still under development and requires field-validation.

Wetland Mapping for Mackenzie Great Bear Sub-basin as part of a Canadian Wetland Inventory that still requires validation[63].

Documented sources of information on the number, location and total area of wetlands was not found.
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