Fisheries Lake Survey

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Name: Birch

Nearest Town: Grand Marais
Primary County: Cook
Survey Date: 09/04/2012
Inventory Number: 16024700

Public Access Information

Ownership Type Description
US Forest Service Carry-In Steep carry-in from Laurentian Divide scenic overlook on the Gunflint Trail (Cook County Road 12). Parking for five vehicles.


Lake Characteristics

Lake Area (acres): 236.31
Littoral Area (acres): 70.7
Maximum Depth (ft): 69
Water Clarity (ft): 17.0 (13-21)

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


Did you know? The state operates 17 hatcheries: 5 for trout and salmon and 12 for coolwater species.

Fish Sampled for the 2012 Survey Year

Species

Gear Used

Number of fish per net

Average Fish Weight (lbs)

Normal Range (lbs)

Caught

Normal Range

Brook Trout Gill net 0.44 N/A 1.23 N/A
Lake Trout Gill net 0.11 0.4 - 3.7 16.81 1.5 - 4.0
Rainbow Trout Gill net 4.78 N/A 1.14 N/A
Smallmouth Bass Gill net 0.22 0.3 - 1.4 0.52 0.6 - 1.5
White Sucker Gill net 2.67 0.8 - 5.3 3.12 1.1 - 2.5
Normal Ranges represent typical catches for lakes with similar physical and chemical characteristics.


Length of Selected Species (Trapnet, Gillnet) Sampled for the 2012 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 0 0 2 2 0 0 0 4
lake trout 0 0 0 0 0 0 0 1 1
rainbow trout 0 0 2 38 0 3 0 0 43
smallmouth bass 0 0 2 0 0 0 0 0 2
white sucker 0 0 0 2 16 6 0 0 24


For the record, the largest Tiger Muskellunge taken in Minnesota weighed 34 lbs., 12 oz. and was caught:

    Where: Lake Elmo, Washington County
    When: 7/7/99
    Statistics: 51" length, 22.5" girth

Fish Stocking Activity

Fish Stocked by Species for the Last Ten Years

Year Species Size Number Pounds
2013 Brook Trout yearlings 5,000 1,247.0
2012 Rainbow Trout yearlings 5,000 1,634.0
2011 Brook Trout yearlings 5,206 1,282.3
2010 Brook Trout yearlings 1,692 231.8
  Rainbow Trout yearlings 3,199 1,103.1
2009 Brook Trout yearlings 4,980 1,853.6
2008 Rainbow Trout yearlings 3,500 1,111.1
2007 Splake yearlings 4,062 796.9
2006 Rainbow Trout yearlings 3,500 1,356.6
2005 Lake Trout yearlings 2,045 187.1
  Lake Trout yearlings 2,020 163.1
2004 Rainbow Trout yearlings 1,750 553.8

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 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

LAKE NAME
County, DOWID
Species Meal Advice Contaminants
Unrestricted 1 meal/week 1 meal/month Do not eat
BIRCH
Cook Co., 16024700
Lake Trout   All sizes     Mercury
Rainbow Trout All sizes        
Smallmouth Bass   All sizes     Mercury
Splake   All sizes     Mercury
White Sucker   All sizes     Mercury

General Population

LAKE NAME
County, DOWID
Species Meal Advice Contaminants
Unrestricted 1 meal/week 1 meal/month Do not eat
BIRCH
Cook Co., 16024700
Rainbow Trout All sizes        
Splake All sizes        
White Sucker 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.

Dioxin
Mercury
PCBS - Polychlorinated biphenyls
PFOS - Perfluorooctane sulfanate


Status of the Fishery (as of 09/04/2012)

Birch Lake is currently managed for rainbow and brook trout. The long range goal (from the 2008 management plan) for rainbow trout is to maintain a rainbow trout population with a minimum gill net catch of 1.0 fish/set, and a minimum mean weight of 1.4 lb/fish. The long range goal for brook trout is a population with a minimum gill net catch of 3.0 fish/set and a minimum mean weight of 0.75 lb/fish. This was the second of two assessments scheduled in the 2008 plan to determine growth and survival of stocked rainbow and brook trout. The current management plan for Birch Lake will be reviewed and revised in March 2014.

Assessments of Birch Lake use a combination of deep and shallow gill net sets. Deep sets target coldwater species, while shallow sets target warm and cool-water species. In DNR Lakefinder reports, catches in those nets have been combined. In addition, 0.25-in-mesh trap nets were used in this assessment to monitor the nearshore fish community. Catches for those nets are not included in Lakefinder reports.

The combined rainbow trout catch in deep and shallow gill net sets (4.78 fish/set) easily met the current long range goal for the species, and fell within the normal range (1.00-6.50 fish/set) for fall assessments of stream trout lakes in this area. The mean weight for rainbow trout taken in gill nets (1.14 lb/fish) fell short of the long range goal, but exceeded the normal range (0.53-1.13 lb/fish) for fall catches in area stream trout lakes. The rainbow trout catch was dominated by one-year-old fish from the 2012 yearling stocking, although a small number of three-year-old fish from the 2010 stocking were also present. Rainbow trout growth over the summer of 2012 had apparently been good. Fish were stocked in the early spring at an average weight of 0.33 lb/fish, while the mean weight for one-year-old fish taken in September was 0.92 lb/fish. Growth for the three-year-old rainbow trout taken in this assessment had been fast; they reached an average length of 18.1 inches at the end of their third year, compared to an area average of 14.3 inches.

Short-term growth and survival of stocked rainbow trout had been relatively high, despite the presence of smallmouth bass. Rainbow trout are well adapted to thrive on an invertebrate forage base. It is possible that smallmouth bass, by decimating minnow populations in this lake, reduced competition faced by rainbow trout for invertebrate forage.

The combined brook trout catch in deep and shallow gill net sets (0.44 fish/set) fell well short of the goal set for the species, and was below the normal range for fall assessments of stream trout lakes in this area (1.50-14.00 fish/set). The size goal was met, since the catch consisted entirely of two- and three-year-old fish from stocking done in 2011 and 2010. Brook trout growth had been somewhat slower than average. Fished reached an average length of 9.1 inches by the end of their second year, compared to an area average of 9.4 inches.

Smallmouth bass have probably had an adverse effect on brook trout survival and growth. Although brook trout yearlings (instead of fingerlings) have been stocked to reduce direct predation from bass, they have not been as large as the rainbow trout yearlings stocked, and some predation may have occurred. Brook trout growth has generally been better when they have had access to a minnow forage base. Loss of minnow populations in this lake probably reduced the potential for good brook trout growth.

The smallmouth bass catch in shallow gill net sets was within the normal range (0.50-1.50 fish/set) for that gear. Only two year classes were represented in the combined assessment catch (two five-year-old fish in gill nets, five one-year-old fish in 0.25-in trap nets), suggesting that smallmouth bass reproductive success or recruitment might be sporadic in this lake.

Despite the lack of suitable habitat, there may still be a few lake trout remaining in Birch Lake. One large fish was taken in this assessment. The temperature-oxygen profile found no portion of the water column with conditions suitable for lake trout (temperature < 55 F, oxygen > 5 ppm), but conditions that may have been at least survivable were found at depths of 27 to 30 ft.

No new undesirable fish species were found in 2012. The white sucker gill net catch was relatively low compared to catches seen in this lake since 1994, and fell within the normal range for shallow sets in stratified assessments in this area (1.23-5.00 fish/set). For the third assessment in a row, no minnows of any kind were taken in 0.25-in-mesh trap nets. Minnows were abundant in Birch Lake prior to the appearance of smallmouth bass.


For more information on this lake, contact:

Area Fisheries Supervisor
1356 Hwy 61 E
Grand Marais, MN 55604
Phone: (218) 387-3056
Internet: Grand Marais Fisheries
E-Mail: GrandMarais.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 B0499 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

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