Current Status and Management Recommendations for the Fishery in the Cloverleaf Chain of Lakes Jason Breeggemann Senior Fisheries Biologist Wisconsin Department of Natural Resources
Outline DNR fisheries surveys How and Why? Results of latest comprehensive fish survey Management goals and objectives
Fish Population Assessments How doe the DNR Sample the Cloverleaf Chain of Lakes
Sampling Schedule Comprehensive fish community survey 4 year rotation 2017 2018 Last comprehensive survey in 2013 2014
Spring Fyke Netting Survey Walleye, northern pike, and muskellunge Shortly after ice out Water temps = 40 50 F Locations that are conducive to spawning Panfish
Spring Electrofishing Survey Largemouth bass and panfish Water temps = 55 70 F Entire shoreline Gamefish and Dip All stations
Length Weight Gender Calcified structures for estimating ages Number of each species Fin clips Stocking origin Recaptures Tags PIT tags in muskellunge What Information We Collect
How the DNR Gauges a Fish Population Metrics Relative abundance (catch-per-unit-effort) Number caught per unit distance or time Total abundance (mark recapture) Number of individuals within the population Proportional stock density Describes size structure of population Balanced fishery = PSD of 40 60 Length frequency distribution Graphical representation of the number of fish within given size classes Growth Mean length at age Mean age at length Recruitment Missing year classes
Metric Analysis Comparison to other fisheries throughout WI Trends within the Cloverleaf Chain through time
Current Status and Trends in the Fisheries of the Cloverleaf Chain
Walleye
Fyke Net Catch Per Unit Effort Walleye Relative Abundance Fyke net: 17 captured 0.2 per net night Low = 8 th percentile Electrofishing: 35 captured 8.3 per mile of electrofishing Moderate = 46 th percentile 0.5 0.4 0.3 0.2 0.1 0.0 2006 2008 2010 2012 2014 2016 2018 Year
PSD Size Structure: PSD Stock size = 10 inches Quality size = 15 inches Fyke Net: PSD = 31 Electrofishing: PSD = 6 120 100 80 60 40 20 Walleye Peak Walleye Abundance Mixed small and large fingerlings Mostly large walleyes but some small Stocking only small fingerlings Declines in catch rates Only 1 walleye <20 inches in 2008 Smallest walleye in 2013 was >23 inches No survival of small fingerlings. All large old fish. 0 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 Year Stocking only large fingerlings Catches still low but dominated by stocked large fingerlings. Too young to be spawning
Number Sampled Walleye Size Structure: PSD Stock size = 10 inches Quality size = 15 inches Fyke Net: PSD = 31 Electrofishing: PSD = 6 6 5 4 3 2 1 0 16 14 12 10 8 6 4 2 0 Fyke Netting 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Electrofishing 10 11 12 13 14 15 16 Length Interval (Inches)
Walleye Management Plan Goal: A walleye population of moderate density with a moderate size structure Objective (Density): Maintain a population estimate of 2 adult walleye per acre and moderate catch-per-unit-effort in spring fyke netting surveys Objective not being met Evidence of survival of recently stocked large fingerlings Hopefully density increases in future Objective (Size Structure): Maintain PSD at 40-60% with 10-15% being 20+ inches Population dominated by smaller individuals Size structure should increase as the 2013 and 2015 year class grow Management Strategy: Continue stocking large fingerling walleyes every other year Consider changing regulation to 18 inch minimum and daily bag limit of 3 to enhance quality of the walleye fishery
Muskellunge
Fyke Net Catch Per Unit Effort Muskellunge Relative abundance: Fyke net 42 captured 34 individuals 0.5 per net night Moderate = 55 th percentile Decreased catches likely due to decreased stocking True abundance: 82 adult muskellunge 0.26 per acre WDNR range (0.1 0.3) 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 2006 2008 2010 2012 2014 2016 2018 Year
PSD Muskellunge Size Structure: PSD Stock size = 30 inches Quality size = 34 inches Fyke Net: PSD = 97 38% of muskellunge captured were > 40 inches High growth potential! 120 100 80 60 40 20 0 1970 1980 1990 2000 2010 2020 Year
Number Sampled Muskellunge Size Structure: PSD Stock size = 30 inches Quality size = 34 inches Fyke Net: PSD = 97 38% of muskellunge captured were > 40 inches High growth potential! 8 7 6 5 4 3 2 1 0 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 Length Interval (Inches)
Muskellunge Management Plan Goal: A muskellunge population of low moderate density with moderate proportions of muskellunge > 40 inches and the potential to grow trophy sized fish. Objective (density): Maintain adult muskellunge densities at 0.2 0.3 per acre in spring population estimate and moderate densities in spring fyke netting surveys. Objective being met Objective (size structure): Of all muskellunge 30 inches and larger, 30 50% should be 38 inches and longer and 10 20% should be 42 inches and longer. Objective being met Management strategies: Continue stocking at a rate of 1 large fingerling muskellunge per acre every 2 3 years. Maintain preferred native habitat including native emergent and submerged vegetation as well as coarse woody habitat in littoral zone.
Northern Pike
Fyke Net Catch Per Unit Effort Northern Pike True Abundance: 268 adult northern pike 0.85 per acre Relative abundance: Fyke net 109 captured 1.3 per net night Moderate = 45 th percentile Causes: Loss of spawning habitat? Poor egg/larval/age-0 survival? Increased harvest? Large fingerlings stocked in 2014 and 2017 4.0 3.0 2.0 1.0 0.0 2006 2008 2010 2012 2014 2016 2018 Year
PSD Northern Pike Size Structure: PSD Stock size = 14 inches Quality size = 21 inches Fyke Net: PSD = 16 Low = 18 th percentile Historically poor growth and size structure 20 18 16 14 12 10 8 6 4 2 0 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 Year
Number Sampled Northern Pike 14 Size Structure: PSD Stock size = 14 inches Quality size = 21 inches Fyke Net: PSD = 16 Low = 18 th percentile Historically poor growth and size structure 12 10 8 6 4 2 0 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Length Interval (Inches)
Northern Pike Management Plan Goal: A moderate density northern pike population with moderate proportions of quality (>21 inches) and preferred size (>26 inches) fish. Objective (density): A relative abundance of 3 6 adult northern pike per net night in spring fyke netting surveys and an adult population estimate of 2 5 adult northern pike per acre. Fewer individuals captured Objective (size structure): Of all northern pike 14 inches and longer in spring fyke netting, 40 60% should be 21 inches and longer and 10 15% should be 26 inches and longer. Mostly small northern pike Historically = slow growth and poor condition Management Strategies: Continue to stock large fingerling northern pike as necessary Enhance northern pike habitat: Promote a diverse mix of native emergent and submerged aquatic plants Northern pike spawn in marshy environments with significant amounts of emergent vegetation Add fish sticks where possible
Largemouth Bass
Electrofishing Catch Per Unit Effort Largemouth Bass Relative abundance: Electrofishing 174 captured 41.1 per mile of electrofishing High = 81 st percentile 45 40 35 30 25 20 15 10 5 0 2006 2008 2010 2012 2014 2016 2018 Year
PSD Largemouth Bass Size Structure: PSD Stock size = 8 inches Quality size = 12 inches Electrofishing: PSD = 60 Moderate = 60 th percentile 70 60 50 40 30 20 10 0 2006 2008 2010 2012 2014 2016 2018 Year
Number Sampled Largemouth Bass Size Structure: PSD Stock size = 8 inches Quality size = 12 inches Electrofishing: PSD = 60 Moderate = 60 th percentile Few bass >15 inches captured Harvest? Slow growth 30 25 20 15 10 5 0 4 5 6 7 8 9 10 11 12 13 14 15 16 Length Interval (Inch)
Largemouth Bass Management Plan Goal: A moderate density largemouth bass population with a moderate proportion of legal sized (>14 inches). Objective (density): A catch per unit effort of 20 30 largemouth bass per mile of electrofishing in spring surveys with 4 8 largemouth bass >14 inches captured per mile of electrofishing. Objective being met Objective (size structure): Of all largemouth bass >8 inches captured in spring electrofishing surveys, 40 60% should be >12 inches, 30 40 % should be >14inches, and 5-10% should be >18 inches. Few large bass captured Management Strategies: Manage for native emergent and submerged plant communities Add additional fish sticks where feasible
Bluegill
Electrofishing Fyke Net Catch Per Unit Effort Bluegill Relative abundance: Fyke net 1,300 captured 15.3 per net night Moderate = 60 th percentile Electrofishing 107 captured 107 per mile of electrofishing Moderate = 56 th percentile 50 250 45 40 200 35 30 150 25 20 100 15 1050 5 00 2006 2008 2010 2012 2014 2016 2018 Year
PSD Bluegill Size Structure: PSD Stock size = 3 inches Quality size = 6 inches Fyke net: PSD = 48 Moderate = 42 nd percentile 70 60 50 40 30 20 10 0 1970 1980 1990 2000 2010 2020 Year
Number Sampled Bluegill Size Structure: PSD Stock size = 3 inches Quality size = 6 inches Fyke net: PSD = 48 Moderate = 42 nd percentile 250 200 150 100 50 0 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 Length Interval (Half Inch)
Bluegill
Bluegill
Bluegill Management Plan Goal: A moderate density bluegill population with a moderate high proportion of harvestable size fish. Objective (density): A catch per unit effort of 10 20 per net night in spring fyke netting surveys and 70 100 per mile of electrofishing in spring bass/panfish electrofishing surveys. Objective being met Objective (size structure): Of all bluegills >3 inches, 40 60% should be >6 inches, 20 40% should be >7 inches and 5 10% should be > 8 inches. Few large bluegills Management Strategies: Evaluate the special panfish regulation in 2021 Control excessive invasive aquatic plants such as Eurasian water milfoil Maintain adequate predator densities to control bluegill recruitment
Black Crappie
Fyke Net Catch per Unit Effort Black Crappie Relative abundance: Fyke net 662 captured 7.8 per net night Moderate High = 69 th percentile 40 35 30 25 20 15 10 5 0 2006 2008 2010 2012 2014 2016 2018 Year
PSD Black Crappie Size Structure: PSD Stock size = 5 inches Quality size = 8 inches Fyke net: PSD = 9 Variable through time! 70 60 50 40 30 20 10 0 1970 1980 1990 2000 2010 2020 Year
Number Sampled Black Crappie Size Structure: PSD Stock size = 5 inches Quality size = 8 inches Fyke net: PSD = 9 Variable through time! 180 160 140 120 100 80 60 40 20 0 Length Interval (Half Inch)
Black Crappie
Black Crappie
Black Crappie Management Plan Goal: A moderate density black crappie population with a moderate high proportion of harvestable size fish. Objective (density): Maintain a catch per unit effort of 5 15 black crappie per net night in spring fyke netting surveys. Objective being met Objective (size structure): Of all black crappie >5 inches, 40 60% should be >8 inches and 10 20% should be >10 inches. Population dominated by smaller individuals Strong 2015 year class! Management Strategies: Manage for native emergent and submerged aquatic plants Add additional fish sticks where feasible Restore shoreland zones to natural plant communities
Other Species of Interest Pumpkinseed High density but few fish >7 inches captured Yellow perch 33 captured in spring fyke netting survey Difficult to effectively sample with fyke nets of electrofishing Rock bass Healthy population comprised of plenty of harvestable size fish
Summary and Management Recommendations Maintain and enhance aquatic habitat Promote native emergent and submerged aquatic plant communities Control invasive plants such as Eurasian water milfoil where possible Add additional fish sticks where feasible Maintain low density high quality muskellunge fishery Continue to stock large fingerlings at rate of 1 per acre every 2 3 years Decent survival of 2013 and 2015 year classes of stocked large fingerlings Highest observed survival of young walleyes since 1980s Continue stocking large fingerlings at a rate of 10 per acre every other year Consider changing regulation to 18 inch minimum and daily bag limit of 3 Continue to monitor panfish populations Maintain moderate density but improve size structure Evaluate special panfish regulation in a couple of years