Lesser Slave Lake

The contents of this online version has not been altered or modified from the original 1990 publication. It is reasonable to assume that much of the data e.g. water levels, camp grounds/boat launches, etc. is out of date. For updated or additional information on any of the lakes in this atlas please go to Environment Alberta's water web site.

Basic Info
Map Sheets83N, 83O
Lat / Long55.4500000, -115.4333333
55°27'N, 115°25'W
Area1,160 km2
Max depth20.5 m
Mean depth11.4 m
Dr. Basin Area12,400 km2
Dam, WeirWeir
Drainage BasinAthabasca River Basin
Camp GroundPresent
Boat LaunchPresent
Sport FishNorthern Pike, Lake Whitefish, Walleye, Yellow Perch
Trophic StatusEutrophic
TP xNo Data µg/L
CHLORO xNo Data µg/L
TDS x111 mg/L
35
Photo credit: Alberta Tourism

Introduction

Lesser Slave Lake is one of Alberta's largest water bodies. It played an important role in the colourful history of the fur trade during the nineteenth century, and at present, it is the site of several excellent recreational facilities and one of Alberta's largest commercial fisheries. The lake is situated in very diverse countryside in Improvement District No. 17, about 300 km northwest of the city of Edmonton. Highway 2 from Edmonton runs along the southern shore and Highway 88 (formerly Highway 67) skirts the eastern shore (FIGURE 1). The drive along the southern shore from east to west is spectacular, as one passes through dense woodland and rolling hills, then flat, open prairie. The towns of High Prairie and Slave Lake are the major urban centres in the area.

The original inhabitants of the Lesser Slave Lake area were either Slave or Beaver Indians. In the mid-1700s, they were displaced by Cree Indians as the Cree moved farther west in search of new sources of fur. The Cree brought with them European weapons and tools, as well as canoes, which were new to western Indians (Alta. Rec. Parks n.d.). The Cree were the first people to use the lake as a transportation corridor.

Sir Alexander Mackenzie learned of Lesser Slave Lake in 1793. He recorded its existence in his journals, but never visited it. In 1799, David Thompson of the North West Company became the first white man to arrive on the shore of the lake (Lombard North Plan. Ltd. 1972). Thompson was responsible for construction of the first trading post in the area, at the junction of the Lesser Slave and Athabasca rivers. By 1802, this post had been relocated to the land that was occupied by the townsite of Slave Lake until 1935, after which the townsite was moved to its present location. The Hudson's Bay Company set up a post nearby in 1815 (Alta. Rec. Parks n.d.) and both companies also established forts on Buffalo Bay at the present townsite of Grouard. The Lesser Slave Lake area was the scene of violent conflict between these rival companies prior to their merger in 1821. Both attempted to gain sole control of the lucrative fur supply, which was considered to be the richest in the whole of Rupert's Land (Lombard North Plan. Ltd. 1972). After the fur resources were depleted, Lesser Slave Lake remained important as a way station for traders and furs travelling to and from the northwest.

A new era began in the early 1900s with the formation of the Northern Transportation Company, which ran steamboats across the lake and provided easy access to the Peace Country. The steamboat Northern Light provided service from 1909 to 1915. When the railroad arrived in 1915, steamboats became obsolete. The Edmonton, Dunvegan and British Columbia Railway Company built a line north from Edmonton, west along the southern shore of Lesser Slave Lake, and then west to the Peace Country (Alta. Rec. Parks n.d.).

At present, there are five Indian reserves on the southern and eastern shores of the lake, and on the outlet, the Lesser Slave River. They are, from west to east, the Sucker Creek (150A), Driftpile (150), Swan River (150E), Assineau River (150F) and Sawridge (150G, 150H) reserves (FIGURE 1). When Treaty No. 8 was signed in 1899, the five Cree bands that resided around the lake were regarded as one entity and the land was administered jointly. Thirty years later, each band became a separate body with its own chief and council. In 1984, the total membership of the five bands was 1,743 people, and the reserves covered a total area of 18,800 ha (Alta. Native Aff. 1986). Near the hamlet of Grouard on Buffalo Bay, members of the Grouard Indian Band live on three reserves: Freeman (150B), Halcro (150C) and Pakashan (150D). About 87 people resided on the 444-ha reserves in 1981.

There are four hamlets, one village and one town on or near Lesser Slave Lake and adjoining Buffalo Bay: the town of Slave Lake, the village of Kinuso and the hamlets of Grouard, Joussard, Faust and the hamlet of Canyon Creek, Widewater-Wagner (FIGURE 1). Slave Lake was originally named Sawridge and was located downstream along the Lesser Slave River. In 1935, the town moved to its present location because of flooding, and in 1938, the town was renamed Slave Lake (Allen 1989). In 1988, its population was 5,611 people. Kinuso was originally called Swan River, but was renamed Kinuso, which is Cree for fish. In 1981, the population of Kinuso was 282 people (Alta. Native Aff. 1986). The Grouard area was a centre for fur trading during the early nineteenth century. The hamlet was given its present name in 1909, when Lesser Slave Lake Settlement was renamed for Monsignor Grouard, the resident priest. The population of Grouard in 1987 was 545 people. Joussard was originally called Indianna, but was renamed for Bishop Joussard. Historically, the hamlet was an important centre for traders, explorers and settlers, a gathering place for Indians and Metis and the site of a Roman Catholic Mission. In 1987, the population of Joussard was 330 people. Faust was once an important centre for the fishing and trapping industry. The main water and land routes for explorers, traders and settlers were located near the hamlet. In 1987, the population of Faust was 399 people. Canyon Creek, Widewater-Wagner is a single hamlet that had a population of 422 people in 1986. Canyon Creek was established in the 1930s as a major mink ranching area, and commercial fishing to supply mink food soon became an important industry. A fish hatchery operated in the community between 1928 and 1944 (Stenton 1989). It raised lake whitefish, which were stocked in lakes throughout the province.

There are two provincial parks on Lesser Slave Lake (FIGURE 2). Both parks provide day-use services year-round and camping services from 1 May to Thanksgiving Day. Hilliard's Bay Provincial Park is located on the northwest shore, 13 km east of Grouard. It has 189 campsites, three group camping areas, sewage disposal facilities, tap water, playgrounds, interpretive programs, a boat launch, a beach and picnic facilities. Swimming, boating, fishing, hiking and cross-country skiing are some of the activities enjoyed at the park. Lesser Slave Lake Provincial Park is located on the northeast shore, 3 km north of the town of Slave Lake, off Highway 88. It has 113 campsites, two group camping areas, sewage disposal facilities, a playground, picnic facilities, a golf course, hiking trails, 5.5 km of sandy beaches and extensive sand dunes. During winter, cross-country skiing on groomed trails and snowshoeing are popular activities. There is no boat launch within the park, but two launches are available just south of the park at an Alberta Environment day-use area at the weir on the Lesser Slave River. Another launch is available in Canyon Creek on the south shore (FIGURE 2).

There are several other recreational facilities on or near the lake. Spruce Point Park is administered by the Spruce Point Park Association. It is located on the south side of the lake about 2 km west and 9 km north of Kinuso (FIGURE 2). The park is open from May to September, and offers 126 campsites, group camping, pump water, sewage disposal facilities, groceries, a beach, a playground and a boat launch. Swimming, boating, fishing and hiking are popular pastimes there. Assineau River Provincial Recreation Area is located east of Kinuso on Highway 2 where the highway crosses the Assineau River. It is open from the Victoria Day week to Thanksgiving Day, and has 21 campsites, pump water and picnic facilities. Lakeshore Campground is located within the hamlet of Joussard. It is administered by the Joussard Area Development Association, and began operations in 1989. The campground is open from the Victoria Day weekend until the end of September, and offers 16 campsites, flush toilets, tap water, sewage disposal facilities, a boat launch, a sand beach, and a day-use area with picnic tables, a shelter and a playground. As well, there is a commercially operated recreational facility at Shaw Point near Hilliard's Bay Provincial Park.

Police Point Natural Area is located off Secondary Road 750 on the eastern shore of Buffalo Bay (FIGURE 1). It was established by Order in Council in 1987. The area is historically important because it contains a section of the Grouard Trail, a major route for traders, missionaries and settlers travelling to the Peace Country. Vegetation in the natural area ranges from extensive wetlands to mature white spruce and trembling aspen forest. The land is rich with wildlife, and there are excellent opportunities for nature observations, birdwatching and outdoor education. The trails that wind through the natural area can be used for hiking in summer and cross-country skiing in winter. There are no facilities on site (Alta. For. Ld. Wild. n.d.[b]).

Lesser Slave Lake is managed for sport, commercial and domestic fisheries. The sport fishery for walleye and northern pike became increasingly popular during the 1980s. The popular Golden Pike Fishing Derby has been held each summer since the early 1980s from the town of Slave Lake. Sport fishing is somewhat limited by the large size of the lake and severe wave action, which frequently makes the use of small boats dangerous. Buffalo Bay, Grouard Channel and the portion of Lesser Slave Lake within 4 km of the mouth of the channel are closed to fishing during a specified period in April and May each year (Alta. For. Ld. Wild. 1989). There are no boating restrictions over most of the lake, but in posted areas such as designated swimming areas, all vessels are prohibited. In other posted areas, power boats are restricted to maximum speeds of 12 km/hour (Alta. For. Ld. Wild. 1988).

Moderate blooms of blue-green algae turn the lake water green during late summer. The extent of aquatic vegetation is limited by heavy wave action, except in Buffalo Bay, where there are extensive weed beds. The lake's western basin is shallow and well mixed by wind during the ice-free season, whereas the eastern basin is deeper and does not mix to the bottom. The water in both basins contains sufficient amounts of dissolved oxygen year-round to support the fish population.

Drainage Basin Characteristics

The drainage basin of Lesser Slave Lake is large and covers an area about 11 times greater than the lake (Tables 1, 2; FIGURE 3). Much of the inflowing water enters the western end of the lake at Buffalo Bay via the South Heart River, which drains the northwestern part of the watershed. Before the river enters Buffalo Bay, it is joined from the south by the East Prairie and West Prairie rivers. On the southern shore of Lesser Slave Lake, the three largest inflows are the Driftpile, Swan and Assineau rivers, which drain the southeastern part of the watershed. Many small creeks and intermittent streams also flow into the lake. The outflow, the Lesser Slave River, is located at the lake's eastern end. It joins the Athabasca River about 75 km downstream of the outlet.

Lesser Slave Lake is a remnant of Lake Peace, a large proglacial lake that formed about 11,500 years ago as the Keewatin glacier retreated (Paetz and Zelt 1974; NW Hydraulic Consult. Ltd. 1983). This extinct proglacial lake was estimated to extend as far west as present-day Winagami Lake, which is now 35 km west of Buffalo Bay. The lake had an elevation of about 687 m above current sea level for a considerable length of time (NW Hydraulic Consult. Ltd. 1983). By about 11,000 years ago, the lake level had dropped to near the present-day level of about 577 m. Much of the area west of Lesser Slave Lake is covered by extensive alluvial and flood-plain deposits. The natural flooding of rivers flowing into Buffalo Bay has often conflicted with agricultural activities in the area. In an effort to reduce flooding, 36 km of the East Prairie, West Prairie and South Heart rivers were channelized between 1953 and 1971. Additional flood control was provided by the South Heart Dam in the early 1950s. Water management projects have continued during the 1980s.

Much of the land north of Lesser Slave Lake and south of Township 76 is level and undulating to gently rolling. The three common soil parent materials are glacial till, organic material and outwash material. Generally, Orthic Gray Luvisols have formed on the till, whereas Podzolic Gray Luvisols have formed on the shallow outwash. Organic soils are mainly the Sphagnum moss type. On the southern shore of the lake along the deltas of the Driftpile and Swan rivers, as well as near the town of Slave Lake, the land is undulating and depressional. Gleyed Dark Gray Luvisols that developed on alluvium are common, as are sedge bogs (Wynnyk et al. 1963). Land in the northwestern and southwestern parts of the drainage basin is gently rolling to rolling and soils are frequently Orthic Dark Gray Luvisols that developed on till. They are intermixed with very large areas of Organic soils. In the west-central part of the watershed, particularly in the High Prairie-Buffalo Bay-Winagami Lake area, the land is level to undulating and the soils, which are mostly Gray Luvisols, have developed on glacial till and alluvial and aeolian deposits (Odynsky et al. 1952).

Most of the cultivated land near the lake lies on the Driftpile and Swan River deltas and in the Joussard-High Prairie-Grouard triangle (FIGURE 1). The main crops are oilseeds (canola), cereal grains (wheat, oats, barley), small seeds (grasses, legumes) and forage crops (clover, legumes, timothy, fescue, broom grass). Production of field peas became increasingly important during the mid-1980s. Livestock production is a major industry; the land near Lesser Slave Lake is the second largest cow- and calf-producing area in the Peace Country (Dist. Agric. 1988).

With the exception of the southern portion, the drainage basin is part of the Dry and Moist subregions of the Boreal Mixedwood Ecoregion (Strong and Leggat 1981). The dominant trees on moderately well-drained Gray Luvisols are trembling aspen in the Dry Subregion and an association of trembling aspen and balsam poplar in the Moist Subregion. White spruce is the main species on imperfectly drained Gray Luvisols and Gleysols, and black spruce and sedges grow on poorly to very poorly drained Organic soils. Around the shore of Lesser Slave Lake, the mixedwood forest is composed of dense young stands of trembling aspen that are associated with balsam poplar, white birch, green alder and white spruce. A history of fire has modified the forest so that white spruce is present in only a few stands (West. Soil Envir. Serv. 1979). An area of Boreal Foothills vegetation is located south of the lake at the headwaters of the Inverness and Driftpile rivers (FIGURE 3). In this area, trembling aspen, balsam poplar and lodgepole pine are the main trees on moderately well-drained Gray Luvisols. In the Swan Hills, which are in the extreme southern portion of the watershed, there is a small area of Boreal Uplands vegetation, where lodgepole pine is the main tree on well to moderately well-drained Luvisols and Brunisols.

Forestry is economically important to the Lesser Slave Lake area. In late 1988, construction of a new pulp mill near the town of Slave Lake was announced. The oil and gas industry is also active, primarily in the Swan Hills, Mitsue Lake and Marten Hills areas and within Lesser Slave Lake Provincial Park (Paetz and Zelt 1974; West. Soil Envir. Serv. 1979).

Lake Basin Characteristics

With a surface area of 1,160 km2, Lesser Slave Lake is one of Alberta's largest water bodies (TABLE 2). The lake is separated into two basins by a stretch of shallow water known as the Narrows (FIGURE 2). The maximum depth of the east basin is about 20.5 m and the maximum depth of the west basin is about 15.5 m. Along the north, west and south shores of the east basin, the lake bottom slopes steeply to a depth of about 17.5 m. Along the east side of the basin, slopes are more gradual. The west basin slopes quite gradually except for stretches along the north and south-central sides. Buffalo Bay is a large, shallow body of water that is joined to the west basin by a narrow channel (FIGURE 1). The bay's surface area varies considerably when water levels fluctuate.

The elevation of Lesser Slave Lake has been monitored since 1923 (FIGURE 4). The lake level has fluctuated over a range of 2.86 m, from a maximum elevation of 578.35 m in 1935 to a minimum elevation of 575.49 m in 1941. Changes in the lake's area and capacity with elevation are shown in Figure 5. At high water levels, flooding occurred along the south and west sides of the lake, where the backshore is shallow and sloping (Alta. Envir. 1988). To resolve the problem, in 1968 the provincial Cabinet decided to purchase all privately owned land adjacent to the lake. Over the following decade, however, residents requested a different solution. In 1978, a ministerial decision to stabilize water levels led to the Lesser Slave Lake Regulation Environmental Impact Assessment study (Alta. Envir. 1979). As a result of this study, the flow capacity of the Lesser Slave River was improved in 1981 and 1982 by construction of eight channel cutoffs. These modifications increased outflow, thereby reducing maximum lake levels. As well, a 30-m-long sheet-pile weir was constructed on the outlet in 1983. It was designed to maintain a minimum lake level of 575.5 m (TABLE 2).

An experimental fish passage facility was constructed in 1983 as part of the weir. It consists of a vertical-slot fishway and two Denil II fishways of 10% and 20% slope. The effectiveness of the three designs was monitored during May and June 1984 (Schwalme and Mackay 1985). Most large fish swam over the weir and through the spillway rather than through the fishways. Of the fish that ascended the fishways, northern pike preferred the two Denil II fishways, whereas longnose and white suckers preferred the vertical-slot fishway.

Lesser Slave Lake is used as a water supply by municipalities, industries and farming operations. In 1988, 11 user groups were licenced for withdrawal (Alta. Envir. 1988).

Water Quality

Detailed information on water quality in Lesser Slave Lake is not available. The Water Quality Branch of the provincial Department of Health collected three samples in August and September of 1970 (Alta. Envir. n.d.[a]), and Fish and Wildlife Division gathered some limnological data prior to 1974 and during the summer of 1975 (Paetz and Zelt 1974; Weisgerber 1977). In February 1989, Alberta Environment collected a single series of samples from 4 depths in the east basin.

Lesser Slave Lake has fresh water that has relatively low alkalinity for a prairie lake (TABLE 3). The dominant ions are bicarbonate and calcium. Turbidity varies with location. High turbidity occurs near inflows during floods, and also results from shore erosion by wave action at high water levels. During the open-water period in 1975, water transparency, as indicated by Secchi depth, varied from 1.0 to 3.5 m in the east basin and 1.5 to 3.0 m in the west basin.

In spring, the shallower west basin becomes ice free before the east basin, and the whole lake is usually ice free by mid-May. In 1975, the average temperature of the water column from May to early August was higher in the west than in the east basin, partly because of the earlier ice-free conditions. As well, the west basin's shallower depth allows greater mixing than in the deeper east basin, where mixing is greatly inhibited below a depth of about 14 m. The west basin was well mixed throughout the open-water period in 1975. In contrast, the east basin was weakly thermally stratified by 18 June 1975 (FIGURE 6). On 7 July, strong winds mixed the water column in the east basin to a depth of almost 15 m, and by 21 July, several windy periods caused the total loss of thermal stratification. The water restratified by 5 August, but was again mixed to the bottom within a week. Ice formation on both basins in 1975 proceeded gradually throughout November, and a solid ice layer had formed by early December.

The two basins have different patterns of dissolved oxygen concentrations throughout the water column. In 1975, the west basin was well mixed for most of the open-water season. Dissolved oxygen concentrations in the east basin, on the other hand, were depleted below a depth of 15 m by 7 July (FIGURE 6). By 5 August, the concentration of dissolved oxygen in water near the sediments had declined to less than 3 mg/L. Subsequent mixing of the entire water column raised the concentration of dissolved oxygen to 8 to 9 mg/L from surface to bottom. In the east basin in February 1989, the concentration of dissolved oxygen declined gradually from 13 mg/L at a depth of 1 m to 0 mg/L at a depth of 18 m (FIGURE 6).

There are no nutrient data available for Lesser Slave Lake during the open-water season. Winter samples from February 1989 indicated a concentration gradient for total phosphorus, from 11 µg/L at a depth of 1 m to 45 µg/L at a depth of 17 m (TABLE 4). The presence of moderate blue-green algal blooms in both basins during summer, a high benthic invertebrate standing crop, and low dissolved oxygen concentrations in the deeper water in the east basin during summer suggest that the lake may be eutrophic.

Biological Characteristics

Plants

The phytoplankton community in Lesser Slave Lake has not been studied in detail. Blue-green blooms (Microcystis sp., Aphanizomenon sp. and Anabaena spp.) have been reported, most notably in the west basin (Miller 1941; Weisgerber 1977).

In 1977, Fish and Wildlife Division listed 28 species of aquatic macrophytes in the lake (TABLE 5). Most of the littoral area is subject to considerable wave action, and submergent weed beds were dominated by large-sheath pondweed (Potamogeton vaginatus), Richardson pondweed (P. richardsonii) and stonewort (Chara spp.). Emergent vegetation was generally sparse and consisted mostly of common great bulrush (Scirpus validus) and sedges (Carex spp.). Large stands of bulrush and a wide variety of submergent and emergent species were present in Buffalo Bay.

Invertebrates

The zooplankton species in Lesser Slave Lake were studied by Fish and Wildlife Division in 1941 and 1976 (Miller 1941; Chymko 1977). In 1976, the zooplankton was sampled weekly from mid-May to late October. The dominant cladoceran in both studies was Daphnia (pulex group). Bosmina sp. was commonly found in 1941 but rare in 1976. The most common copepods were Diaptomus ashlandi, Acanthocyclops vernalis and Diacyclops bicuspidatus thomasi. Diacyclops is important because it is the first intermediate host of the tapeworm Triaenophorus crassus. The cysts of this parasite infest the lake whitefish and cisco in Lesser Slave Lake (Miller 1952[a]).

Only the deep-water benthic invertebrate fauna of Lesser Slave Lake have been sampled (Weisgerber 1977). Based on weekly samples taken by Fish and Wildlife Division from 21 May to 27 October 1975, the mean biomass was 33.9 g/m2 (wet weight). Midges (Chironomidae) dominated the benthic community and there were small amounts of fingernail clams (Pisidium) and aquatic earthworms (Oligochaeta). Higher densities of benthic organisms were found in the west basin than in the east basin. Two unusual species of crustaceans, Mysis relicta and Pontoporeia affinis, have also been reported in Lesser Slave Lake (Paetz and Zelt 1974). These species are usually restricted to deeper, less productive lakes.

Fish

The fish community of Lesser Slave Lake includes lake whitefish, cisco, mountain whitefish (rare), Arctic grayling (rare), northern pike, burbot, longnose sucker, white sucker, emerald shiner, spottail shiner, trout-perch, brook stickleback (rare), yellow perch, walleye and spoonhead sculpin (rare). Lake trout were abundant in the lake in the early 1900s but were extinct by the early 1940s (Paetz and Zelt 1974).

The commercial, domestic and sport fisheries at Lesser Slave Lake are managed through a quota allocation system. The number of domestic licences issued from 1959 to 1978 varied from a low of one in 1962 to a high of 55 in 1978. Catch statistics for the domestic fishery have not been recorded. The Lesser Slave Lake fishery has also been subject to extensive illegal fishing, either out of season or with illegal gear. Illegal use of gear outnumbered legal use during a period in the mid-1960s when the fisheries collapsed (Ash and Noton 1979). No accurate estimates of the illegal catch are available.

Lesser Slave Lake has a long history of commercial fishing, but records were not kept prior to 1942. Historically, the most important commercially harvested species were lake whitefish, cisco and walleye (Alta. Rec. Parks Wild. 1976). Smaller amounts of northern pike, yellow perch, burbot and suckers were also taken. At present, lake whitefish, suckers and northern pike account for most of the total catch. Between 1981/82 and 1987/88, the average total catch of 510,028 kg/year comprised 57% whitefish, 15% suckers, 12% northern pike, 9% burbot, 6% walleye and 1% cisco (Alta. For. Ld. Wild. n.d.[a]).

Whitefish and walleye catches were highest prior to the mid-1960s, when both fisheries collapsed. The collapse of the whitefish fishery may be attributed partly to overfishing, which was the result of illegal harvest and the harvest of immature fish in the small-sized nets set for cisco (Zelt 1977). It was also partly due to high exploitation during natural periods of low population size (Bell et al. 1977). The growth rate and condition of whitefish declined substantially from the 1940s to the 1970s (Handford et al. 1977). Reduced growth and poor condition may have been caused by increased competition with suckers for food. The heavy exploitation of whitefish and cisco may have allowed an increase in sucker populations when food normally eaten by whitefish and cisco became available for consumption by suckers (Dietz and Krujewski 1978). It is not known, however, whether sucker populations actually increased as whitefish and cisco populations declined. In 1978, an increase in the size of the sucker fishery was proposed so that the size of the population could be reduced (Berry 1978), but since the market for suckers has not developed, an increase in sucker catch has not occurred.

Since the 1960s, the whitefish and walleye populations have recovered to a large extent. During the 1980s, both populations sustained good commercial harvests (Walty 1988). In 1972, several years after the collapse of the whitefish fishery, the small-mesh cisco fishery in the lake was closed. Subsequently, the whitefish population showed a strong recovery. The whitefish quota was increased from 68,000 kg/year in 1972, to almost 250,000 kg/year in 1979, and to 500,000 kg in 1988 (Wallace and McCart 1984; Stenton 1989). The walleye population increased because walleye habitat in Buffalo Bay was stabilized, the small-mesh net fishery in Lesser Slave Lake was closed in 1972, and areas in the western region of the lake were closed to commercial fishing. By 1988, the commercial quota for walleye had been raised to 65,000 kg/year from the 1972 quota of 9,070 kg/year (Wallace and McCart 1984).

Cisco were heavily exploited until the early 1970s when the population collapsed. They were primarily used for mink food by area fur ranchers (Bishop 1970). In 1954, 106,300 mink were raised on 220 ranches, mostly along the southern shore of the lake. By 1975, only two ranches, with 1,455 mink, were operating. The mink industry declined because of a decline in demand for fur combined with competition from Scandinavian and Russian furs. The final collapse of this industry was accelerated by the decline in the supply of cisco from Lesser Slave Lake (Stenton 1989). The collapse of the cisco fishery was caused by overfishing and, possibly, by variations in lake water levels and siltation from oil development activities in the Swan Hills (Bishop 1970). Although the cisco population has recovered to some extent since the 1970s, commercial catches have remained low because of lack of demand and because of the larger-sized mesh used in the fishery (Walty 1988; Stenton 1989).

Cisco and lake whitefish are important intermediate hosts of the tapeworm Triaenophorus crassus. After the tapeworm releases eggs in the spring, the larvae that hatch must be eaten by the copepod Diacyclops bicuspidatus thomasi to survive. If the host copepod is eaten by a whitefish or cisco, the larvae form cysts in the flesh of the fish. If the infested fish are then eaten by a northern pike, the adult tapeworm develops in the pike's intestine. The parasite problem was researched extensively by Miller during the 1940s (Miller 1952[b]). To date, no method of controlling cyst numbers has been found (Walty 1988). Whitefish from Lesser Slave Lake contain more than 80 cysts per 45 kg of fish, and, although edible, are considered to be poor quality and are sold only for commercial products such as fish cakes.

The sport fishery in Lesser Slave Lake is becoming increasingly popular. In 1985, a summer creel survey was conducted at eight access points around Lesser Slave Lake (summarized in Hildebrand and Ash 1986). It was estimated that anglers spent 51,337 hours fishing and caught 12,896 walleye, 15,552 northern pike and 3,861 yellow perch. Almost 78% of the angling pressure occurred at the western end of the lake. In 1986, a more intensive survey was undertaken, but only at the three western access points (Hildebrand and Ash 1986). In 1986, 65% of the anglers interviewed sought walleye, 8% sought northern pike, 0.4% sought yellow perch and 27% had no preference. About 21% of the total number of anglers caught walleye and 33% caught northern pike. Of the fish caught, 6% of the walleye, 44% of the pike and 8% of the suckers were released. Angling success at the western end of the lake was lower in 1986 than in 1985 (TABLE 6), perhaps because of unseasonably cold, wet, windy weather during July. In 1986, the harvest rate for walleye was 0.26 fish/angler-hour (TABLE 6), but survey personnel indicated that some anglers under-reported their catch and that there was a substantial illegal harvest as well. The average walleye harvested weighed about 1 kg, and the largest weighed 2.1 kg. The 1978 and 1980 walleye age-classes dominated the fishery. The average catch rate for northern pike in 1986 was 0.21 fish/angler-hour. The mean pike weight was 1 kg and most fish harvested were less than 5 years old. The average catch rate for yellow perch was only 0.04 fish/angler-hour and the average perch harvested weighed 334 g. Perch ages were not recorded in the survey.

Wildlife

Waterfowl surveys were carried out on Lesser Slave Lake in 1976 and 1977 (Alta. Envir. 1978). The best waterfowl habitat is located along the west, north and south shores of the west basin, along the bays on either side of the Swan River delta in the east basin and in Buffalo Bay. In May, more waterfowl use the west end of the lake than the east end. The most abundant ducks sighted were Mallards, Lesser Scaup, White-winged Scoters, Common Goldeneye and Buff lehead. A large gull colony was located on the western shore of the lake and tern and Western Grebe colonies were sighted on the point of land in the Driftpile River Indian Reserve.

Wildlife data are available for the two provincial parks (Lombard North Plan. Ltd. 1972; Smith 1976; Bradley 1980). In Lesser Slave Lake Provincial Park, more than 170 species of birds have been recorded. Colonial nesters in the park include Eared Grebes, Black and Common terns, and Ring-billed and Franklin's gulls. During migratory periods, Yellow-billed Loons have been sighted. Yellow Rails are present in marshy areas and several Bald Eagles nest in the spruce trees on Dog Island. Eighteen mammal species inhabit the park. The main large mammals are moose and white-tailed deer. Mule deer are present in small numbers and woodland caribou are sometimes sighted in the northeast section of the park. The major carnivores are wolves, coyotes, lynx and wolverines and the minor carnivores are fishers, weasels and otters. The park is prime territory for American black bears, and grizzly bears are also sighted occasionally. In Hilliard's Bay Provincial Park, over 100 bird species and 14 mammal species have been sighted.

Buffalo Bay and its surrounding area provides habitat that ranges from extensive wetlands to mature forests. The diverse plant communities at Police Point Natural Area support a wide array of animals and birds, including over 100 species of nesting birds. In the marshes, ducks such as Common Goldeneye and Mallards, shorebirds such as Killdeer and Spotted Sandpipers, and other birds such as Red-necked Grebes, gulls, Sora and Long-billed Marsh Wrens nest and feed (Alta. For. Ld. Wild. n.d.[b]).

M.E. Bradford and J.M. Hanson

References

Alberta Environment. n.d.[a]. Envir. Assess. Div., Envir. Qlty. Monit. Br. Unpubl. data, Edmonton.

-----. n.d.[b]. Tech. Serv. Div., Hydrol. Br. Unpubl. data, Edmonton.

-----. n.d.[c]. Tech. Serv. Div., Surv. Br. Unpubl. data, Edmonton.

-----. 1978. Lesser Slave Lake environmental overview, Vol. 1. Plan. Div. Unpubl. rep., Edmonton.

-----. 1979. Lesser Slave Lake regulation environmental impact assessment, Vol. 1: Main report. Plan. Div., Edmonton.

-----. 1988. Lesser Slave Lake outlet control works review executive summary. Draft manuscript. Plan. Div., Edmonton.

Alberta Forestry, Lands and Wildlife. n.d.[a]. Fish Wild. Div. Unpubl. data, Edmonton.

-----. n.d.[b]. Police Point, an Alberta natural area. Alta. For. Ld. Wild. Publ. No . 1/211. Pub. Ld. Div., Edmonton.

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