Mavis Lake

Cook County, Minnesota - DNR stocking history, depth and survey data

Minnesota · Minnesota Department of Natural Resources (DNR) · DOW 16052800

DNR records show 5 stocking entries at Mavis Lake since 2016, most recently brook trout fingerlings in 2024 (1,000 fish).

• Mavis Lake has 5 DNR stocking records across 5 years (2016-2024): brook trout (5).
• The most-stocked species by count is brook trout: 4,790 fish on record.
• Maximum depth 55 ft; surface area 9 acres, 3 littoral acres, 0.5 miles of shoreline, per the DNR lake survey.
• Average water clarity (Secchi depth) 18.8 ft.
• Fish species DNR lists here: brook trout.
• 1 public access on the DNR list.
• Most recent DNR fish survey: September 6, 2016 (standard survey).
• Cook County, nearest town Grand Marais; DNR lake number (DOW) 16052800.

Stocking history

⁸ fish cooperatively purchased, raised, and/or stocked by U.S. Fish and Wildlife Service.

Public accesses

DNR fish survey, 2016

Catch per net (CPUE) is the DNR survey's count per gill net or trap net set; higher means more of that species were sampled, not a fishing forecast. Top species per gear shown; where we have no verified common name for a DNR code, the code itself is shown.

Mavis is a designated stream trout lake that has been stocked with trout since 1959. This was the first of two standard surveys scheduled in the current (2014) lake management plan to determine whether the current stocking program was producing a satisfactory Brook Trout population. The current plan calls for stocking 1,000 Brook Trout fingerlings annually, with a goal of maintaining a minimum gill net catch of 5.0 fish/net, with at least two catchable-sized (over 10 inch) year classes present. In small lakes like Mavis, where the number of gill net sets used is very low, little value can be placed on catches in any single survey. The catch in this survey fell short of the long range goal, and was barely within the normal range (1.25-14.00 fish/gill net) for fall surveys of stream trout lakes in this area. Two catchable-sized year classes (2013 and 2011) were included in the catch, and it was encouraging to see some survival of fish to five years of age. Too few fish were taken to describe their growth rates with any confidence. The failure to sample any one or two-year-old fish, which should have been large enough to have been taken in gill nets used in this survey, may suggest poor survival of recent stockings, either due to stocking mortality, or predation from the larger Brook Trout present. Brook Trout have been stocked annually in this lake since 1980, and the stocking quota has been set at 1,000 fingerlings/stocking (100 fingerlings/acre) since 1990 (it had been higher earlier). Three assessments have been done since 1990, and gill net catches in each case have been very low (the 2016 catch was the highest in that period). This is a difficult lake to set a standard gill net in without having it drop into deep waters lacking enough oxygen for fish (because of steep drop-offs along the entire shore), but pains have been taken in the last two assessments to keep all (or most) of each set in shallower waters. A high catch in a 1989 assessment (11.00 fish/net) showed that Mavis Lake could produce higher numbers of fish. Other than Brook Trout strain changes, nothing has changed in Mavis Lake, or in the way it has been managed, since 1989, other than a reduction in stocking quota. At 100 fingerlings/acre, the current quota is still fairly high for a lake of this size; most area Brook Trout lakes are stocked at a lower density (and less frequently). Other than a single White Sucker collected in 1971, no undesirable fish species, and no species other than trout (and minnows), have ever been found in Mavis Lake. The lake retains excellent water quality…

Minnesota DNR survey narrative, September 6, 2016.

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