Survey Method

Black Otter Lake was sampled according to spring netting (SNI) protocols as outlined in the statewide lake assessment protocol. The primary objective for this sampling period is to count and measure adult northern pike. However, we also used this sampling period to asses other species including yellow perch, largemouth bass, bluegill, and black crappie.

Fyke nets were deployed in areas of the lake that contained spawning habitat or were likely travel areas for northern pike. All newly captured northern pike were marked with anchor (Floy) tags in the dorsal fin. All captured game and panfish were identified to species and measured for length. A subsample of fish were weighed and age structures (anal spines) were collected from northern pike for age and growth analysis.

Fish metrics used to describe fish populations include total abundance (mark and recapture popu-lation estimate for northern pike), proportional stock density, catch per effort, length frequency distribution, and mean length at age for northern pike.

2008 Spring Netting (SNI) Summary Report

Black Otter Lake

Outagamie County (WBIC 315600)

Fish Metric Descriptions

Catch per unit effort (CPUE) is an index used to measure fish population relative abundance which simply refers to the number of fish captured per unit of distance or time. For netting surveys we typically quantify CPUE by the number and size of fish per net night. CPUE indexes are compared to statewide data by percentiles and within lake trends. For example, if a CPUE is in the 90th percentile, it is higher than 90% of the other CPUEs in the state.

Total abundance is a metric that describes population size and is estimated by mark and recapture. In our study, during spring netting, a portion of the northern pike pop-ulation is captured, marked (with a partial fin clip), and released. During follow-up surveys, another portion is captured and the number of marked individuals within the sample is counted. The proportion of marked and unmarked fish is used to estimate the size of the population.

Proportional Stock Density (PSD) is an index used to describe size structure of fish. It is calculated by dividing the number of quality size fish by the number of stock size fish for a given species. PSD values in the 30 to 50 percent range generally describe a balanced fish population. PSD indexes are compared to statewide data by percen-tile and to within lake trends.

Length frequency is a graphical representation of the number of fish captured by either 1/2 inch or one inch size intervals. Smaller fish (or younger age classes) may not always be represented in the length frequency due to different habitat usage or gear sampling limitations.

Introduction and Survey Objectives

In 2008, the Department of Natural Resources conducted a fyke netting survey of Black Otter Lake to assess the fisheries community prior to a draw down to control invasive aquatic plants. Primary sampling objectives were to characterize species composition, rela-tive abundance, and size structure of target fish species. The following report is a brief summary of the survey results Acres: 75 Shoreline Miles: 3.2 Maximum Depth (feet): 9 Lake Type: Drainage (impoundment) Public Access: 1Public Landing Regulations: Statewide default regulations

Ryan Koenigs—Fisheries Biologist Aaron O’Connell - Fisheries Technician

Wisconsin Dept. of Natural Resources

625 E. County Rd. Y, Suite 700 Oshkosh, WI 54901

Ryan Koenigs Phone: 920-303-5450 E-mail: Ryan.koenigs@wisconsin.gov

WISCONSIN DNR CONTACT INFO.

Survey Information

Site location Survey Dates Water Temp.

(F) Target Species

No. of Nets

Gear Net Nights

Black Otter Lake 4/11/2008 - 4/15/2008 38 - 40.4 Northern Pike, Panfish 5 Fyke Net 19

Relative Abundance (Catch per Unit Effort)

Species Total No. Captured

CPUE (no per net night)

Statewide Percentile

Rank

Abundance Rating

2016

BLACK CRAPPIE 106 5.6 63rd Moderate

BLUEGILL 934 49.2 84th High

LARGEMOUTH BASS 80 4.2 95th Very High

NORTHERN PIKE 255 13.4 95th Very High

PUMPKINSEED 45 2.4 62nd Moderate

YELLOW PERCH 41 2.2 55th Moderate

BULLHEAD 61 3.2 - -

WHITE SUCKER 1 0.05 - -

CHANNEL CATFISH 1 0.05 - -

GOLDEN SHINER 48 2.5 - -

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Total Abundance (Mark and Recapture Population Estimate

Species Number Marked

(Netting)

Number Sampling

Events (Netting)

No. Recap-tures

(Netting)

Schnabel Population Estimate

(95%)

No per Acre

Abundance Rating

NORTHERN PIKE

185 5 69 313

(257 - 400) 4.2 Moderate

Size Structure Metrics

Species Total Average Length

(Inches) Length Range

(Inches) Stock and Quality

Size (inches) Stock No Quality No PSD Percentile Rank Size Rating

LARGEMOUTH BASS 80 13.1 6.1 19.0 8.0 and 12.0 74 52 70% 46th Moderate

NORTHERN PIKE 255 22.2 12.0 - 35.6 14.0 and 21.0 185 120 65% 75th Moderate-High

Black Otter Lake (WBIC 315600) - Summary Report Continued

Gamefish Summary Page 2

Gamefish Summary Northern Pike

Relative abundance metrics were at very high levels relative to the statewide average, while the population estimate of 4.2 adult northern pike/acre is mod-erate relative to statewide averages. The size structure observed within the population was at moderate levels compared to statewide data, with the aver-age pike measuring 22.2”. Overall, 9.7% of the fish captured were larger than 26”. Age and growth data indicated that both the male (76.5%) and female (88.5%) populations were dominated by 3 year old fish. Further, growth data indicated that females have the growth potential to exceed 36” (largest fish collected was 35.6”), while the average male is estimated to reach a maximum length of 25.5”.

Largemouth Bass

Largemouth bass were captured at very high catch rates relative to statewide data and size structure metrics indicated moderate-high size structure. 52.5% of the largemouth bass collected during the survey were larger than the 14” minimum length limit, which is an indication of good growth and a quality size structure. The largemouth bass, and northern pike, benefit from abundant forage in the form of small panfish.

White Clay Lake (WBIC 326400) - Summary Report Continued

Gamefish Summary

Black Otter Lake (WBIC 315600) - Summary Report Continued

Panfish Summary

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Size Structure Metrics

Species Total Average Length

(Inches) Stock and Quality

Size (inches) Stock No Quality No PSD Percentile Rank Size Rating

BLUEGILL 934 6.0 3.0 and 6.0 inches 838 447 53% 44rth Moderate

BLACK CRAPPIE 106 7.0 5.0 and 8.0 inches 96 27 28% 22nd Low

PUMPKINSEED 45 5.4 3.0 and 8.0 inches 43 9 21% 24th Low

Length Range (Inches)

2.7– 8.8

4.5 - 11.3

3.9 - 6.9

YELLOW PERCH 41 9.1 6.1 - 11.7 5.0 and 8.0 inches 41 31 76% 92nd Very High

Panfish Summary Bluegill

Bluegill catch rates were high relative to statewide data, while size structure metrics were moderate relative to statewide data. The largest bluegill captured was 8.8”, which demonstrates growth potential, but overall the blue-gill population was dominated (67.7%) by fish <6.5”.

Black Crappie

Black crappie catch rates were moderate when compared to statewide data, but a poor size structure was observed. There were a number of crappie larger than 10” captured in the sample, but the majority of the fish were under 8” in length (71.7%). It appears that there is a relatively strong year class of young crappie that hopefully will provide quality fishing opportunities in the future.

Yellow Perch

Catch rates of yellow perch were moderate relative to statewide data and a quality size structure was observed. There was a wide-spread of lengths within the yellow perch sample with a strong contribution of 9.0-9.4” fish.

Stocking History

Species Year Age Mean Length Number Stocked

BLUEGILL  1972  ADULT  5  1440 

BLUEGILL  1973  ADULT  5  5146 

BLUEGILL  1974  ADULT  3  3105 

BLUEGILL  1977  ADULT  ‐  2200 

BLUEGILL  1979  ADULT  ‐  1800 

BLUEGILL  1985  ADULT  3  900 

BLUEGILL  1990  YEARLING  4  720 

BLUEGILL X UNKNOWN  1991  ADULT (BROODSTOCK)  5  17 

LARGEMOUTH BASS  1972  FINGERLING  1  5000 

LARGEMOUTH BASS  1973  FINGERLING  3  7500 

LARGEMOUTH BASS  1976  FINGERLING  3  5000 

LARGEMOUTH BASS  1977  FINGERLING  3  5000 

LARGEMOUTH BASS  1978  FINGERLING  3  4000 

LARGEMOUTH BASS  1978  FINGERLING  1  1000 

LARGEMOUTH BASS  1990  YEARLING  9  50 

LARGEMOUTH BASS  1991  FINGERLING  2.8  750 

LARGEMOUTH BASS  1992  FINGERLING  4.6  650 

LARGEMOUTH BASS  1993  FINGERLING  1  14000 

LARGEMOUTH BASS  1994  FINGERLING  1.9  40950 

NORTHERN PIKE  1972  FRY  1  165000 

NORTHERN PIKE  1976  FRY  ‐  100000 

NORTHERN PIKE  1977  FRY  ‐  100000 

NORTHERN PIKE  1978  FRY  ‐  100000 

LARGEMOUTH BASS  1997  LARGE FINGERLING  6  100 

LARGEMOUTH BASS  1998  SMALL FINGERLING  2  2000 

LARGEMOUTH BASS  1995  FINGERLING  3.9  6000 

NORTHERN PIKE  1991  FINGERLING  7.9  400 

NORTHERN PIKE  1992  FINGERLING  8  150 

NORTHERN PIKE  1994  FINGERLING  1.5  20000 

YELLOW PERCH  1973  ADULT  5  2322 

YELLOW PERCH  1977  YEARLING  ‐  5000 

YELLOW PERCH  1978  ADULT  ‐  2800 

YELLOW PERCH  1979  YEARLING  ‐  5000 

YELLOW PERCH  1990  ADULT  8  30 

YELLOW PERCH  1998  YEARLING  7  6500 

YELLOW PERCH  2002  YEARLING  6  3200 

Black Otter Lake (WBIC 315600 - Summary Report Continued

Management Options and other Information

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