HomeMy WebLinkAboutOtto R23 - fish survey 2-12-24View of Otto Lake, November 2023
Fish Survey of Otto Lake,
Hennepin County, Minnesota in 2023
Survey Dates: November 6 - 7, 2023
MnDNR Permit Number: 35657
Prepared for:
Nine Mile Creek
Watershed District and
MnDNR
February 12, 2024
Prepared by:
Steve McComas
Jo Stuckert
Connor McComas
Blue Water Science
St. Paul, MN
Fish Survey of Otto Lake,
Hennepin County, Minnesota in 2023
Summary
Otto Lake is an 10 acre lake located in Hennepin County, Minnesota.
On November 6-7, 2023, a fish survey was conducted by Blue Water Science using standard
trapnets was implemented on Otto Lake. The objective of the fish survey was to characterize
existing fish structure and assessing potential impacts of fish on water quality in Otto Lake.
A total of 11 fish species were sampled. The dominant fish species were black bullheads. Small
pumpkinseed sunfish were also common in Otto Lake in 2023 (Table 1). Goldfish were
observed at relatively low densities.
Table 1. Trapnet fish survey results for November 7, 2023.
Trapnet Results
Fish per Net
2023
(n=4)
Black bullheads 96
Black crappies 0.3
Bluegill sunfish 9.8
Fathead minnow 63
Golden shiner 16
Goldfish 6.3
Green sunfish 1.5
Mud minnow 0.5
Pumpkinseed sunfish 59.3
Shiner minnow 0.3
Stickleback minnow 0.3
Turtles 0.3
TOTAL FISH 253
Number of Fish Species 11
Figure 1. Black bullheads and minnows were dominant in
Otto Lake in November 2023.
Otto Lake Fish Survey - 2023 1
Conclusions
Currently, black bullheads dominate the Otto Lake fishery. Fish feeding activities can produce
elevated nutrients at high densities resulting in high phosphorus concentrations. However,
aquatic plants are present and this is an indicator that fish probably are not disrupting
sediments in their food search and may have minimal water quality impacts through sediment
activities. In 2022, the maximum depth of Otto Lake was less than 2 feet. When Otto Lake has
low water levels, it likely winterkills over winter.
Management options would appear to be:
1. Passive management. Collect water quality, plant, zooplankton, and fish data. See if
surrounding ponds could be contributing to restocking Otto with fish.
2. Because Otto Lake frequently winterkills, stocking of fish probably would not be cost effective
and is not recommended at this time.
Figure 2. Representative pictures from the Otto Lake fish survey in November 2023.
Otto Lake Fish Survey - 2023 2
Fish Survey of Otto Lake,
Hennepin County, Minnesota in 2023
Introduction
Otto Lake is a 10-acre shallow lake, located in Hennepin County, Minnesota. In November
2023, the Nine Mile Creek Watershed District sponsored a fish survey conducted by Blue Water
Science under permit number 35657 granted from the MnDNR. The objectives were to
characterize the fish community in Otto Lake.
Methods
Four mini trapnets were sampled for one night for a total of four lifts to survey fish in Otto Lake.
The trapnet was a MnDNR-style with a 2 x 3 feet square frame with two funnel mouth openings
and 50-feet lead. Net mesh size was 3/8 inch. Four standard trap nets were set on November 6,
2023. Four nets were fished for the following 1 day (November 7, 2023). Trapnet locations are
shown in Figure 3.
Figure 3. Map of trapnet sets in Otto
Lake.
Otto Lake Fish Survey - 2023 3
Results
Fish Results: Eleven fish species were sampled in Otto Lake on November 7, 2023 (Table 2).
Black bullheads were abundant at over 96 fish/net and were found up to 5.5 inches long, but
most black bullheads were ranging in length from 3.5 to 4 inches (Table 3). Goldfish were
present at 3 inches or less but at low densities.
Turtle Results: A painted turtle was sampled in one of the trapnets. The natural shoreline around
Otto Lake indicates that painted turtles likely do well.
Table 2. Otto Lake trapnet results for the fish survey conducted in November 2023.
Fish Captured (November 6-7, 2023) Total Catch Fish per Net
(n=4)Net 1 Net 2 Net 3 Net 4
Black bullhead 13 20 351 1 385 96
Black crappie 1 1 0.3
Bluegill sunfish 4 1 34 39 9.8
Fathead minnow 25 30 195 250 63
Golden shiner 2 37 23 62 16
Goldfish 2 21 2 25 6.3
Green sunfish 4 2 6 1.5
Mud minnow 1 1 2 0.5
Pumpkinseed sunfish 12 5 89 131 237 59
Shiner minnow 1 1 0.3
Stickleback minnow 1 1 0.3
TOTAL FISH 29 56 534 390 1,009 252
Painted turtle 1 1 0.3
Table 3. Otto Lake fish length distribution for November 7, 2023.
Otto Black
bullhead
Black
crappie
Bluegill Fathead
minnow
Golden
shiner
Goldfish Green
sunfish
Mud
minnow
Pumpkin-
seed
Shiner
minnow
Stickle-
back
minnow
<3 15 38 220 20 16 199 1
3 6 1 5 4
3.5 29 2 1 10 1
4 67 4 1 1 23
4.5 10 2 2 1 5
5 3 7 2
5.5 5 1 3
6
6.5
7
7.5
8
Measured 135 1 39 220 43 20 6 2 237 1 1
Counted 250 30 19 5
TOTAL 385 1 39 250 62 25 6 2 237 1 1
fish/net
(4 nets)96.3 0.3 9.8 62.5 15.5 6.3 1.5 0.5 59.3 0.3 0.3
Otto Lake Fish Survey - 2023 4
Representative Fish Species of Otto Lake
Black bullhead Black crappie
Bluegill sunfish Pumpkinseed sunfish
Minnows Mud minnow
Otto Lake Fish Survey - 2023 5
Appendix
Minnesota DNR Fish Survey Notification
Otto Lake Fish Survey - 2023 6
No Fish Survey in Otto Lake, Hennepin County,
In 2022 Due to Low Water Conditions
Prepared by Steve McComas, Blue Water Science, February 14, 2023
No fish survey was conducted by Blue Water Science in Otto Lake in 2022 because of the low water
level and inability to set nets or to seine. Submerged aquatic plants were observed to be growing in
Otto Lake. Even if fish are present at the end of 2022, shallow water (mostly less than 6 inches deep)
would result in a fishkill over the 2022-2023 winter.
Otto Lake conditions in 2022 are shown below.
Otto Lake Fish Survey - 2023 7