Bertha Lake is 334 acres in size and is part of the Whitefish chain of lakes in northern Crow Wing County. While there is no public access on Bertha, access may be gained via channel from Clamshell Lake or Whitefish Lake. Bertha Lake has a maximum depth of 64 feet with 43% of the lake 15 feet or less. The lakeshore is heavily developed with 147 homes/cabins along nearly 3.9 miles of shoreline.
Even though walleyes aren't stocked directly in Bertha, a walleye fishery exists due to the connection with Whitefish Lake which is stocked with fry and fingerlings. The walleye catch rate of 2.9/gill net is average when compared to similar lakes. The size of walleyes was impressive, with a 22.3" and 4.2 lb average. Fish up to 29.9" were caught with nearly 97% of the fish 14" or larger.
Northern pike numbers are well above average compared to similar lakes with a catch rate of 14.4/gill net. The average length of these fish was 20.3" with a weight of 2.0 lbs. There were fish up to 35.2" sampled with the potential for larger fish to exist due to an abundance of tullibee (cisco), which are an important forage fish. Tullibee (cisco) catch rates were also above average at 23.8/gill net.
Largemouth bass were caught at a rate of 0.7/gill net. The average size of these fish was 12.6" and 1.1 lbs. Only one smallmouth bass was caught which was 16.7" and 2.6 lbs. Although standard survey nets don't sample largemouth bass effectively, electrofishing was conducted on other lakes on the Whitefish chain where the catch rate was 112.5/hr. The average size was similar to Bertha with fish up to 18.7" sampled during electrofishing. Given the connection of the lakes it can be assumed that there is fish movement among basins.
Bluegill were sampled at a rate of 29.9/trap net in 2011. Their average length was 6.8". Overall, 52% of bluegill were 7" or larger. Black crappie abundance was relatively low, with a catch rate of 0.6/trap net and only 0.3/gill net. The black crappies in the gill nets had a decent average size of 11.1". The average size for black crappies in trap nets was slightly smaller at 8.8".
Lake whitefish represent another species that anglers may target. They were sampled at a rate of 0.9/gill net. Their size was decent, with an average length of 20.1" and 3.0 lbs. Fish up to 23.8" were caught during the survey.
Some other fish species sampled during the survey included bowfin (dogfish), brown bullhead, greater redhorse, hybrid sunfish, pumpkinseed, rock bass, shorthead redhorse, silver redhorse, white sucker, yellow bullhead, and yellow perch. While conducting seining and backpack electrofishing, various other species were sampled including johnny darter, banded killifish, blackchin shiner, bluntnose minnow, and green sunfish.
- Zebra Mussel
Recreational activities such as recreational boating, angling, waterfowl hunting, and diving may spread aquatic invasive species. Some aquatic invasive species can attach to boats, while others can become tangled on propellers, anchor lines, or boat trailers. Many species can survive in bilge water, ballast tanks, and motors or may hide in dirt or sand that clings to nets, buckets, anchors, and waders. Fortunately, completing simple steps can prevent the transport of aquatic invasive species.