LAKE MANAGEMENT PLAN

Transcription

1 LAKE MANAGEMENT PLAN Region Area DOW Number County DOW Lake Name Acreage 2 Duluth F St. Louis Aerie Lake DOW: 149 Plan: 139 Long Range Goal: Manage for largemouth bass with electrofishing catch rates of 60.0 per hour of on time and a PSD between 40 and 60. Manage for bluegill with trapnet catch rates of 20.0 per lift and a PSD between 30 and 60. Operational Plan: 1. Conduct future investigations as needed. 2. Minimize impacts to aquatic resources by providing recommendations during permit review. 3. Continue to allow private walleye stocking of any Minnesota strain. Mid Range Objectives: Monitor the fish community. Potential Plan: Evaluate ability to enhance public platted road into carry down access with signage and off road parking or provide a similar public access at another location. NARRATIVE: (Historical perspectives various survevs; past manaqement; social considerations; Dresent limitinq factors; survev needs; land acquisition; habitat develo~ment and protection; commercial fishen/; stockinq Dlans; other manaqement tools; and evaluation plans) Check the appropriate boxes below: BWCAW Superior National Forest Chippewa National Forest Leech Lake Indian Reservation 1854 Ceded Territory 1837 Ceded Territory C] Fond du Lac Indian Reservation C] Voyageurs National Park Primary Species Management: Largemouth Bass, Bluegill Area Supervisor Signature: Secondary Species Management: Black Crappie, Northern Pike, Walleye Date: Regional Manager Signature: Date:

2 NARRATIVE: Aerie Lake is a 139 acre lake located near Alborn, Minnesota with 69% (96.6 acres) littoral area and a maximum depth of 37 feet. Aerie Lake is in lake class 10 with an area priority rating of 3 on a scale of 114 (14 being highest). VARIOUS SURVEYS: Full Surveys: 1959,1979,1992,1995 Population Assessments: 1973, 1984, 1988, 2005 Largemouth Bass Spawning Survey: 1990 Largemouth Bass Electrofishing Surveys: 1996 Recreational Use Survey: A total of 15 fish species were collected in Aerie Lake using gillnets, trapnets, electrofishing, and seining between 1959 and 2005 (Table I). Gillnet catch rates in 1984 were not used for comparison due to insufficient sampling effort (< 3 nets). All interquartile range comparisons are for lake class 10. PAST MANAGEMENT: Largemouth bass fry and fingerlings were stocked between and 1943 and fingerlings were again stocked in 1962 and 1967 in Aerie Lake (Table 2). Shoreline seining and assessment trapnet catches indicated the presence of largemouth bass in the 1970's. Largemouth bass spring night electrofishing catchperuniteffort (CPUE) was 61.6 per hour of on time in 1996, which exceeded the interquartile range (1 5.7 to 47.8) when compared to other Duluth Area bass populations. Although a sufficient sample of largemouth bass was collected (N = 27), only six fish were larger than eight inches and therefore, proportional stock density (PSD) was not calculated. A strong 1994 yearclass comprised 78% of the sampled fish (Table 3), and was responsible for the skewed distribution and small size (mean length of 8.6 inches). Length at age 4 was 12.6 inches in 1996 and represented fast growth when compared to other Duluth Area bass populations. A largemouth bass spawning survey in 1990 concluded shoreline substrate was suitable for largemouth bass spawning and that the south and west shores provided the best spawning habitat. Sunfish fingerlings were stocked in Aerie Lake between 1912 and 1942 (Table 2). Bluegill trapnet CPUE ranged from 0.8 per lift in 1973 to 48.3 per lift in 1992 (Figure 2). All documented catch rates except 1973 and 1992 were within the interquartile range ( ). Bluegill PSD ranged from 14 in 1992 to 74 in 2005 and represented good size potential (Figure 3). Mean length increased from 5.0 inches in 1992 to 6.4 inches in Length at age 4 ranged from 4.3 inches in 2005 to 4.9 inches in 1992 and represented average growth when compared to other Duluth Area lakes. Age analysis revealed consistent recruitment in all years except 1992 (Table 3) with strong yearclasses in 1987, 1989, 1998, and Black crappie fingerlings were stocked in Aerie Lake between and 1943 (Table 2). Black crappie trapnet CPUE ranged from 0.8 per lift in 2005 to 13.0 per lift in 1973 (Figure 2). All

3 documented catch rates except 1959, 1988, and 2005 were within or above the interquartile range (1.66.8). Black crappie PSD ranged from 9 in 1973 to 68 in 1995 and represented variable size potential (Figure 3). Mean length increased from 7.6 inches in 1992 to 8.7 inches in Length at age 4 was 5.6 inches in 1995 and 7.8 inches in 2005 and represented an increase from slow to fast growth when compared to other Duluth Area lakes. Analysis of age distribution revealed erratic recruitment, but good 1987 and 1989 yearclasses (Table 3). Northern pike fingerlings, yearlings, and adults were stocked in Aerie Lake in 1961 and 1962 (Table 2). Northern pike gillnet CPUE ranged from 0.3 per lift in 1959 to 7.8 per lift in 1988 (Figure 1). All documented catch rates since the 1959 survey were within or above the interquartile range (1.35.3). Northern pike PSD ranged from 7 in 1988 to 59 in 1992 and represented variable size potential (Figure 3). Mean length ranged from 17.4 inches in 1995 to 22.0 inches in Length at age 4 ranged from 20.6 inches in 2005 to 28.9 inches in 1995 and represented average to fast growth when compared to other Duluth Area lakes. Analysis of age distribution revealed consistent recruitment (Table 3). Aerie Lake is one of five Duluth management area lakes known to have silver pike present. Survey crews sampled silver pike in both the 1995 and 2005 investigations, and anglers have reported a number of them over the years. In the spring of 2006, a 16 pound silver pike was reported caught by an angler from Aerie Lake. Various life stages of walleye were stocked in Aerie Lake by the Minnesota Department of Natural Resources (MN DNR) between 1912 and 1996 (Table 2). Historic walleye catch rates have generally been at or below the first quartile (0.8) with only the first survey reporting a higher catch rate (Figure 1). Attempts at establishing a walleye fishery through fry and fingerling stocking met with minimal success and the MN DNR opted to discontinue stocking walleye in In response, the Aerie Lake Property Owners Association began stocking yearling walleye between 1998 and 2005 (Table 2). Walleye gillnet CPUE increased slightly from 0.2 per lift in 1996 to 1.0 per lift in 2005, indicating limited stocking success (Figure 1). Mean length of walleyes also increased from 17.8 inches in 1995 to 18.8 inches in Length at age 4 increased from 15.0 inches in 1995 to 15.9 inches in 2005 and represented average to fast growth when compared to other Duluth'Area lakes. Mean length of walleyes also increased from 17.8 inches in 1995 to 18.8 inches in Almost all walleye aged correlated to years stocked for the period of (Table 3). Ages of privately stocked fish are unknown; therefore their contribution to the population could not be determined. Yellow perch yearlings were stocked in Aerie Lake to increase the forage population in 1986 (MN DNR) and in 2001 (Aerie Lake Association; Table 2). Yellow perch gillnet CPUE ranged from 0.5 per lift in 1973 to 30.0 per lift in 1959 (Figure I). All documented catch rates were within or above the interquartile range (0.57.0). Yellow perch PSD ranged from 0 in 1984, 1992, and 1995 to 17 in 1979 and represented poor size potential. Mean length was similar in 1992, 1995, and 2005 (range of ). Length at age 4 was 5.5 inches in 1992 and 5.3

4 inches in 1993 and represented average growth when compared to other Duluth Area lakes. Analysis of age distribution in 1992 and 1995 revealed strong 1988 and 1991 yearclasses constituting nearly 89% of all yellow perch captured. SOCIAL CONSIDERATIONS: Aerie Lake does not have a developed public access. A 33foot wide public undeveloped road exists west of the section line between T52 R18 Sections 8 and 9 and south of Aerie Lake Road and was platted in In it's present condition, this road is considered marginally accessible due to dense vegetation and lack of signage and parking. Development on Aerie Lake more than doubled between 1959 (23 cabins) and 1973 (54 cabins). The number of dwellings increased gradually after 1973 to a high of 67 in An aerial recreational use survey of 67 Duluth Area lakes was conducted between 1999 and 2000 and estimated approximately 2,844 total angling hours on Aerie Lake, of which 66% (1,872 h) was open water angling. This resulted in 19.1 hlacre and fishing pressure was categorized as moderate to heavy. The Citizen LakeMonitoring Program (CLMP) has been active on Aerie Lake since This program combines the technical resources of the Minnesota Pollution Control Agency and the volunteer efforts of citizens to collect water quality data to monitor lake eutrophication status. The CLMP measured water clarity for Aerie Lake from 1975 to Aerie Lake has a Property Owners Association that is very active in walleye management. The association has obtained permits to stock walleye in 1998, 1999, 2000, 2001, 2003, and 2005 (stocked in 2006). Also, under a permit issued from the MN DNR, volunteers from the Aerie Lake Association removed 26 suckers in 2000, 11 8 in 2001, and 24 in 2002 as an attempt to reduce white sucker population density so walleye spawning grounds would be less disturbed. Over this threeyear period, a total of 168 suckers weighting approximately 756 pounds were removed. This equates to about 5.4 pounds per acre over 3 years, or 1.8 pounds per acre per year. By comparison, MN DNR studies have shown that at least 80% of the suckers present must be removed for effects to be meaningful, although even then, the benefits may be shortlived. In a lake like Aerie, this would translate into removing approximately 1500 suckers weighing about 7000 pounds for several consecutive years (50 pounds per acre per year). Consequently, the MN DNR discontinued the trapnetting permit in Aerie is unlikely to support a large walleye population because physical characteristics of the lake are not conducive to walleye reproduction or survival. Aerie Lake will have walleye present in low numbers with stocking, but neither rough fish removal nor intensive walleye stocking will change the nature of this lake. Aquatic plant harvesting (mechanical) and chemical treatment (Hydrothol 191 granular) for 1750 feet of shoreline was conducted in 1991 and 1992 (under MN DNR APM permit) to control aquatic vegetation species such as largeleaf pondweed, watershield, and water celery.

5 Several individual permits were also issued in LIMITING FACTORS: Results from the CLMP water quality samples indicated that the trophic status for Aerie Lake is currently mesotrophic. Average secchi reading (feet) has remained stable except for 1993 when it was 20.0 feet (Figure 4). Water analysis conducted by the MN DNR showed an increase in total phosphorus from mg/l in 1992 up to mg/l in 1995 and a corresponding increase in chlorophyll a from 6.2 ppb (parts per billion) in 1992 to 22.0 ppb in Since Aerie Lake is highly developed, efforts to ensure compliance of septic systems and minimize use of chemicals and/or fertilizers will help to protect water quality. Shoreline best management practices (BMP's) should be implemented. Walleye spawning habitat was limited to a few points along the island and east of the island. LAND ACQUISITION: The public platted road from Aerie Lake Road is undeveloped and does not allow reasonable access to the lake in its current condition. Signage and development of a carry down public access that provides limited off road parking would be desirable at the road site or another location. HABITAT DEVELOPMENT AND PROTECTION: Minimize impacts to aquatic resources by providing recommendations during permit review. COMMERCIAL FISHERY: None. STOCKING PLANS: Continue to allow private walleye stocking of any Minnesota strain. SURVEY AND EVALUATION PLANS: Conduct future investigations as needed. OTHER MANAGEMENT TOOLS: None.

6 Table 1. Species sampled in Aerie Lake, Survey Type: FS=FuII Survey; PA=Population Assessment; SA=Special Assessment

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8 Table 3. Age distribution for fish species sampled from Aerie Lake in 1992, 1995, 1996, and " <== Years Stocked * sampling gears combined ** Percent contribution determined for 1983 to 1996 only. Age of privately stocked fish unknown.

9 Figure 1. Historical gillnet catch rates from Aerie Lake, su 25 * 20 a2 'a L '& 15 L Q) f, 10 k 5, O Walleye O O Yellow Perch Northern Pike White Sucker Nets Sets

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11 Figure 3. Historical PSD for fish sampled from Aerie Lake, () indicates that PSD was not calculated due to sample size less than 10.

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