Factors affecting Fish Populations at Turtle, Brightsand and Helene Lakes - Gord Sedgewick - Fisheries Biologist, Ministry of Environment - posted August 19, 2014
At the 2014, Annual General Meeting of the Turtle Lake Watershed Inc., Gord Sedgewick, Fisheries Biologist
with the Ministry of Environment presented and discussed the history and factors affecting fish population at
at number of lakes in the region. Gord has provided some of the information from his presentation that is
specific to Turtle Lake, Brightsand Lake and Helene Lake. Just click on the lake you are interested in to view
FISH RESOURCE IN TURTLE LAKE
Turtle Lake Bathymetry and Fish Habitat
Turtle Lake lies in a NE-SW direction and has a maximum length of slightly over 20 km and a maximum width of 5-6 km. The lake is relatively shallow with an average depth of 5.6 m and a maximum depth of 14.3 m. The deepest part of the lake is in the centre of the lake west of Sunset View cottage subdivision. Areas less than 5 m in depth account for 52% of the total water surface. The northern half of the lake, including Mikinak Lake at the very northern end, is very shallow (mostly less than 0.6 m).
Growth of emergent vegetation covers about 20% of the littoral zone (shallow water area near shore) in the southern half of the lake. Bulrush is the predominant species, followed by cattail, sedge and phragmites. Emergent macrophytes cover a large portion of the northern half of the lake.
Fish species of most interest to lake users (i.e. northern pike, walleye, yellow perch and lake whitefish) all use the littoral zone for spawning and rearing purposes. Northern pike and yellow perch generally prefer vegetated areas for spawning and rearing. The many weed beds in the shallow northern half of the lake provide a diverse habitat not only for these two, but also for other fish species.
Because walleye are not overly abundant in Turtle Lake, it appears that habitat is marginal for walleye. Lack of suitable spawning streams rather than nursery grounds is probably the main reason. Areas within the lake that can be considered as potential walleye spawning habitat are those windswept areas with bottom substrate ranging from sand and gravel to gravel and rocks of various sizes. The increase in abundance of walleye in recent years can likely be attributed mostly to the stocking program, but there is some indication that walleye have adapted to spawning in the lake as well. About 80% of the shoreline in the southern half of the lake consists of some combination of rocks, sand and gravel.
Overall, Turtle Lake has a good mix of habitat for a variety of fish species.
An in-depth fisheries survey was conducted on Turtle Lake in 1964-65, and the findings are reported in the Fisheries Branch Technical Report “Report on Biology of the Turtle Lake Fishery” (Dr. W.W. Sawchyn, 1967).
Other fisheries studies on the lake include:
Ø Turtle Lake Angling 1980 (Fisheries Technical Report 82-1)
Ø Evaluation of Walleye Fingerling Stocking Programs in Three Saskatchewan Lakes (Fisheries Technical Report 91-4)
Ø Turtle Lake Habitat Mapping, 1997 (Dr. W.K. Liaw, 1999)
Additionally, Fisheries Branch personnel have test netted (with gill nets, and more recently with trap nets) Turtle Lake on numerous occasions – 1955, 1973, 1976, 1979, 1982, 1985, 1992, 1997, 2000, 2003).
Ten species of fish were recorded from Turtle Lake during the 1964-65 fisheries survey.
Large Species Forage (smaller)Species
Northern pike Spottail shiner
Walleye Iowa darter
Lake Whitefish Brook stickleback
Common white sucker
The fish stocking program on Turtle Lake dates back to 1927, and has been ongoing with some regularity over the past 80 years. Two species have been the focus of the stocking program in an effort to bolster their populations – walleye and lake whitefish.
From 1932 – 1962, over 14 million walleye fry (newly hatched) were stocked in the lake. The fisheries survey of 1964-65 indicated poor stocking success, so the stocking program was terminated. But due to high angler demand for walleye in the late 1960s, the walleye stocking program was re-introduced. From 1969 – 2004, another 22 million walleye fry as well as 461,300 walleye fingerlings (about 5 cm long) were stocked. Currently, Turtle Lake is stocked with approximately 500,000 walleye fry each spring.
Whitefish stocking started in 1927 and was discontinued in 1984. During this period, tens of millions of whitefish fry were stocked. The most extensive stocking occurred from 1969 – 1980 when 13 million fry were stocked in the lake.
Turtle Lake is a heavily utilized recreational lake, with over 1500 cottages. Northern pike is the mainstay of the recreational fishery, with many large fish taken annually by anglers. The abundance of natural pike habitat, as well as the abundance of forage fish, allows the pike population to flourish. The pike population has always been maintained through natural reproduction in the lake.
Walleye is the choice of many anglers, but the number of angling size fish has been low through most of the past 40-50 years, despite the large numbers of walleye stocked in an effort to increase the population. There are recent indications that the walleye stocking program is beginning to show signs of success. The latest trap net (live capture and release) survey by Fisheries Branch in 2003 caught a significant number of walleye, represented by several age classes from 2 – 8 years of age. Walleye represented by the 4 – 8 year age classes represent the ideal size fish for angling, and there were lots of these fish in the trap nets. Anglers also catch burbot and lake whitefish during the ice fishing season.
Perch, which is another favorite sport fish species in Saskatchewan, is fairly abundant in Turtle Lake but does not grow large enough in the lake to be of angling size. Because of its small size, it serves as a forage fish for pike and walleye.
A commercial fishery for whitefish was in existence on Turtle Lake since the year 1900 (Dominion Alberta and Saskatchewan Commission Report 1910-1911). There were a few declines in the fishery during the first half of the 20th century with some population declines lasting up to five years.
Turtle Lake had a commercial quota for whitefish of 75,000 lb annually, and production averaged 60,000 lb per year until 1963. Local residents from around the lake participated in the annual winter fishery; a fish packing plant was located at Moonlight Bay on the west side of the lake. The whitefish population collapsed in 1963 and production averaged only 5200 lb/year until 1977, after which the lake was no longer fished commercially. The reason for the collapse is unknown, but a combination of fishing pressure and intermittent spawning success may have been responsible. There has been some indication the whitefish spawn in the shallow north end of the lake and in Mikinak Lake, both of which are subject to winterkill (therefore the eggs, which are laid in late fall, would not survive through the winter). The extensive stocking program was not successful at revitalizing the population.
The Turtle Lake Monster
Much has been reported and written over the years about the Turtle Lake “monster” (although nothing has been reported in recent years). Over the years, people fishing in the open water have reported sightings of a big “thing” swimming near their boat. Could it have been a lake sturgeon?
Lake sturgeon inhabit the Saskatchewan River system, and the outflow from Turtle Lake flows via the Turtle River directly into the North Saskatchewan River. It is not inconceivable during some years of very high outflow that sturgeon could have found their way from the North Saskatchewan up the Turtle River and into Turtle Lake. Sturgeon have a very long life span, so the few that may have entered the lake could have stayed there for many decades. And of course, the longer they lived in the lake, the larger they grew. Sturgeon are bottom feeding fish, so they wouldn’t often be sighted near the surface.
The presence of a few slake sturgeon is the most plausible explanation for the numerous reported sightings of a “monster” swimming in the waters of Turtle Lake. Having said this, sturgeon have never been caught in any test netting surveys, nor in any commercial fishing nets, so there is no conclusive evidence of their presence in the lake. However, there are similarities between Turtle Lake and Candle Lake in regards to their connection to the Saskatchewan River system; in the case of Candle Lake, a few large lake sturgeon have actually been caught which verifies they were able to find their way upstream and take up residence in the lake. But for Turtle Lake we’ll likely never know for sure!
Gord Sedgewick, Biologist for Saskatchewan Environment provided attendees at the Turtle Lake Watershed Inc. 2010 Annual General Meeting with an interesting and current presentation about the status of the fishery in Turtle Lake. After setting 11 gillnets and 3 trap nets in the lake in early July, Sedgewick reported that his team had caught 1,473 fish of which 53% were walleye and 9% were Northern Pike. "Turtle Lake can now be called a predominantly walleye fishery and the walleye are of all ages and sizes with many ranging from 5 to 8 pounds", reported Sedgewick. He went on to report that "they are very healthy with lots of fat on them." When asked if he knew if walleye were reproducing naturally in Turtle Lake, Sedgewick said that he had not completed the research to determine that.
Walleye have been stocked annually in Turtle Lake, since the early 90's and it appears those efforts are paying off. Sask Environment places 500,000 walleye fry in Turtle Lake every spring, however none were stocked this year. Going forward, Sask Environment plans on stocking 1 million walleye fry in Turtle Lake every other year.
(Photos: Top Left, Merv Swanson, President of the Turtle Lake Watershed Inc. and Gord Sedgewick, display walleye, Top Right: Gord Sedgewick presenting to attendees.)