Fisheries Lake Survey

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Name: Conchu

Nearest Town: Ely
Primary County: Lake
Survey Date: 05/29/2007
Inventory Number: 38072000

Public Access Information

Ownership Type Description
US Forest Service Portage

Lake Characteristics

Lake Area (acres): 49.52
Littoral Area (acres): 26
Maximum Depth (ft): 67
Water Clarity (ft): 16

Dominant Bottom Substrate: N/A
Abundance of Aquatic Plants: N/A
Maximum Depth of Plant Growth (ft): N/A

Did you know? Fishing piers are installed on lakes to provide opportunities for shore fishing.

Fish Sampled for the 2007 Survey Year


Gear Used

Number of fish per net

Average Fish Weight (lbs)

Normal Range (lbs)


Normal Range

Brook Trout Gill net 1.25 N/A 0.22 N/A
Normal Ranges represent typical catches for lakes with similar physical and chemical characteristics.

Length of Selected Species (Trapnet, Gillnet) Sampled for the 2007 Survey Year

Species Number of fish caught in each category (inches)
0-5 6-8 9-11 12-14 15-19 20-24 25-29 30+ Total
brook trout 0 4 1 0 0 0 0 0 5

For the record, the largest Brown Trout taken in Minnesota weighed 16 lbs., 12 oz. and was caught:

    Where: Lake Superior, St. Louis County
    When: 6/23/89
    Statistics: 31.4" length, 20.6" girth

Fish Stocking Activity

Fish Stocked by Species for the Last Ten Years

Year Species Size Number Pounds
2010 Brook Trout fingerlings 4,006 106.0
2009 Brook Trout fingerlings 1,547 29.6
2008 Brook Trout fingerlings 4,640 140.6
2007 Brook Trout fingerlings 3,999 119.0
2006 Brook Trout fingerlings 4,014 116.0

Stocking Notes
1 - indicates fish purchased and stocked by private citizens and sporting groups.
2 - indicates fish purchased by the DNR for stocking.

Stocking Fish Sizes
Fry - Newly hatched fish that are ready to be stocked usually called "swim-ups". Walleye fry are 1/3 of an inch or around 8 mm.
Fingerling - Fingerlings are one to six months old and can range from a size of one to twelve inches depending on the species. Walleye fingerlings range from three to eight inches each fall.
Yearling - Yearling fish are at least one year old. A one-year-old fish can range from three to twenty inches depending on the species. Walleye yearlings average from six to twelve inches.
Adult - Adult fish are fish that have reached maturity. Depending on the species, maturity can be reached at two years of age. Walleye reach maturity between the ages of four and six years.

Fish Consumption Guidelines

These fish consumption guidelines help people make choices about which fish to eat and how often. Following the guidelines enables people to reduce their exposure to contaminants while still enjoying the many benefits from fish.

Pregnant Women, Women who may become pregnant and Children under age 15

County, DOWID
Species Meal Advice Contaminants
Unrestricted 1 meal/week 1 meal/month Do not eat
Lake Co., 38072000
Brook Trout   All sizes     Mercury

General Population

County, DOWID
Species Meal Advice Contaminants
Unrestricted 1 meal/week 1 meal/month Do not eat
Lake Co., 38072000
Brook Trout All sizes        

DOWID - MN DNR, Division of Waters' lake ID number.

Contaminants listed were measured at levels that trigger advice to limit consumption.

Listing of consumption guidelines do not imply the fish are legal to keep, MN DNR fishing regulations should be consulted.

PCBS - Polychlorinated biphenyls
PFOS - Perfluorooctane sulfanate

Status of the Fishery (as of 05/29/2007)

Conchu Lake is in Ecological Lake Class 4, which consists of 47 lakes in northeast Minnesota that are small, deep, and have clear and soft (unmineralized) water.

Conchu Lake was thermally stratified on 05/29/2007 and retained good oxygen for trout (more than 5 ppm) to a depth of 34 ft, where the temperature was 40 F. Testing done in several investigations on Conchu Lake prior to 1988 showed that in midsummer, 5 ppm oxygen was retained to a depth of about 20 ft, where the temperature was about 50 F, and the Secchi water clarity ranged from 7 ft to 12 ft.

Conchu Lake is in the Boundary Waters Canoe Area Wilderness. It has an inlet from Uranus Lake with a waterfall that prevents upstream fish movement. The outlet to the Kawishiwi River has a beaver dam and a 4 ft falls limiting fish movement. Lake bottom substrates along the shoreline of Conchu Lake are mostly rubble, ledgerock, and gravel. Aquatic plants are sparse and grow to a depth of 10 ft; sedges and waterlilies are the most common plants.

Conchu Lake was poisoned with rotenone by a helicopter with a spray apparatus in the fall of 1984, killing most of the northern pike, white sucker, rock bass, yellow perch, pumpkinseed sunfish, and largemouth bass that were present. Uranus Lake was poisoned at the same time, removing populations of minnows. Some white sucker apparently survived the 1984 poisoning, as sucker were captured in the 1985 assessment. Largemouth bass up to 14" were reported by anglers in 1989 and were captured in the 1990 assessment and several subsequent assessments. A few large northern pike were reported by anglers in the early 90's and were captured in assessments in 1994 and 2003. Although northern pike catches were low, their sizes have been very large (up to 41") and trout were found in their stomachs.

Following the 1984 poisoning, Conchu Lake was initially stocked with splake and brook trout. Splake stocking was discontinued in Conchu Lake and all other managed stream trout lakes in the Boundary Waters Canoe Area Wilderness after 1988 at the request of the U.S. Forest Service because they were not considered to be an indigenous species. Brook trout fingerlings have been stocked annually since 1988.

The 2007 trout assessment consisted of four gillnets set in late May. Six previous trout assessments, each consisting of 2-4 gillnet sets, were done from 1986 through 2003.

Five brook trout, ranging in length from 6-9", were captured in the 2007 assessment; all had been stocked (air-dropped from a float plane) the previous fall. Four of these trout had insects and amphipods in their stomachs, while the remaining trout had an empty stomach. The total catch of trout by weight in 2007 of 0.3 lb/gillnet was much lower than the median catch of 6.6 lb/gillnet in all assessments on this lake and was lower than the median catch of 3.7 lb/gillnet in recent assessments of 25 stream trout lakes (excluding mine pit lakes) in the Tower Fisheries Management Area.

No white sucker, northern pike, or largemouth bass were caught in the 2007 assessment. Anglers have reported catching largemouth bass and occasional large northern pike in Conchu Lake in recent years.

For more information on this lake, contact:

Area Fisheries Supervisor
650 Hwy 169
Tower, MN 55790
Phone: (218) 753-2580
Internet: Tower Fisheries

Lake maps can be obtained from:

Minnesota Bookstore
660 Olive Street
St. Paul, MN 55155
(651) 297-3000 or (800) 657-3757
To order, use C5082 for the map-id.

For general DNR Information, contact:

DNR Information Center
500 Lafayette Road
St. Paul, MN 55155-4040
TDD: (651) 296-6157 or (888) MINNDNR

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