Lake information report

Name: Conchu

Public Access Information

Lake Characteristics

Fish Sampled for the 2007 Survey Year

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

Fish Stocking Activity

Fish Stocked by Species for the Last Ten Years

Fish Consumption Guidelines

These fish consumption guidelines help people make choices about which fish to eat and how often. Following the guidelin es 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

General Population

DOWID - MN DNR, Divion 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.

Dioxin
Mercury
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 E-Mail: Tower.Fisheries@state.mn.us	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 Internet: www.dnr.state.mn.us E-Mail: info.dnr@state.mn.us	Turn in Poachers (TIP):     Toll-free: (800) 652-9093