Oconto Falls Pond, Oconto County, Wisconsin

Fisheries Survey Report, 2018

Waterbody Identification Code: 449300

Tammie Paoli Fisheries Biologist

Wisconsin Department of Natural Resources Peshtigo, Wisconsin

NOVEMBER 2018

Oconto Falls Pond, Oconto County, Wisconsin Fisheries Survey Report, 2018

Tammie Paoli

Fisheries Biologist NOVEMBER 2018

SUMMARY Lake and location Oconto Falls Pond, Oconto County, T28N R19E Sections 22, 23, and 26. It is located in the township and city of Oconto Falls. Physical/chemical attributes Surface acres: 180 acres Maximum depth: 28 feet Lake type: flowage/impoundment Water chemistry: hard water, slight alkalinity, low transparency Littoral substrate: sand and muck Shoreline: 5.5 miles Aquatic vegetation: Dominant vegetation (2017 survey by WDNR Water Resources staff) includes

coontail (Ceratophyllum demersum), wild celery (Vallisneria), common waterweed (Elodea canadensis), flat-stem pondweed (Potamogeton zosteriformis), and white water lily (Nymphaea odorata).

Aquatic invasives: Aquatic forget-me-not, curly-leaf pondweed, Eurasian watermilfoil, flowering

rush, Chinese mystery snails, and zebra mussels Purpose of surveys Baseline lake survey Tier I assessment Dates of fieldwork Fyke netting survey conducted April 25, 2018 through May 4, 2018. Electrofishing survey conducted May 22, 2018. Fishery Largemouth bass, smallmouth bass, northern pike, muskellunge, bluegill, black crappie, rock bass, yellow perch, pumpkinseed, green sunfish, walleye, white sucker, brook trout, bullhead, common carp, bowfin, and golden shiner are present. Acknowledgements Data collection for the 2018 survey was completed by WDNR fisheries staff Ronald Rhode, Tammie Paoli, and Ben Ewoldt. Fish aging and data entry was completed by Ronald Rhode and Ben Ewoldt.

BACKGROUND Oconto Falls Pond is an impoundment of the Oconto River with an area of 180 acres and a maximum depth of 28 feet. The littoral area is primarily sand and muck. The existing dam at the downstream end of Oconto Falls Pond is referred to as Oconto Falls Upper Hydroelectric Project (FERC #2523). It was constructed in 1915, has a head of 28 feet, and is owned by NEW Hydro, Inc. The Oconto Falls Lower Hydroelectric Project (FERC #2689) is located 1,950 feet downstream from Oconto Falls Upper dam. The FERC license for the upper dam expires in 2023 and NEW Hydro has already initiated the re-licensing process. There are three boat landings on the flowage. The East Side boat launch is owned by the City of Oconto Falls. NEW Hydro owns a boat landing just upstream of the dam on the east side. NEW Hydro also owns approximately 0.5 miles of shoreline including the West Side boat launch which provides access, a pavilion, beach, and walking trails. All three boat ramps are managed by the City of Oconto Falls and all include fishing piers to provide shore fishing opportunities. An ADA compliant pier was installed by the Oconto Falls Lions Club in 2012 on property owned by the City of Oconto Falls adjacent to Highway 22. An unmarked 60-foot wide public access walk-in parcel exists along West Highland Drive. The 5.5 miles of shoreline is moderately developed as homes and seasonal cottages. A total of 57 piers were counted as part of the Oconto County Lakes Project1. The upper portion of the flowage is fairly undeveloped and mostly private property. NEW Hydro owns 51 acres in the upstream riverine portion that includes approximately 0.25 miles of frontage, as well as 20 acres that includes another 0.25 miles of shoreline in the middle portion of the flowage. Eurasian watermilfoil was reported in 2000, while zebra mussels were verified in 2005. Curly-leaf pondweed, flowering rush, and Chinese mystery snails were verified in 2013. The Oconto Falls Lions Club is a non-governmental group that is active with improvements to Oconto Falls Pond. In 2013 and 2014, that group worked with the Oconto Falls High School agriculture class to construct 25 fish cribs using concrete blocks, pallets, and brush. These fish cribs are grouped within four clusters in the lower portion of the flowage, in approximately 15 feet of water. The Oconto County Lakes Project is a county-wide grant funded project being completed by Oconto County Land Conservation Department, University of Wisconsin – Stevens Point, UW-Extension, and Wisconsin DNR. Over several years, 60 lakes with public access in Oconto County will have an individual Lake Management Plan developed. The County will have an Operational Strategy & Plan to help County staff members achieve an overall goal of “having the healthiest waters in Wisconsin”. Oconto Falls Pond was one of nine waterbodies included in the first round of planning, and at the time of writing this report, the Lake Management Plan is being drafted. Current fishing regulations follow the general inland regulations. The Oconto Falls Lions Club has stocked various panfish species in recent years (Table 1). Fisheries surveys conducted from 1995 to 2018 are shown in Table 2. The previous comprehensive survey on Oconto Falls Pond was completed in 20072. 1 http://www.co.oconto.wi.us/i_oconto/pu/72f2f4f71245/ocontosummary2018.pdf

2 Rowe, D. 2009. Oconto Falls Pond, Oconto County Wisconsin Fisheries Survey Report, 2007.

METHODS

Four standard 3’ x 6’ hoop fyke nets with ¾” bar, 1 ½” stretch mesh were set on April 25, 2018 (Figure 1). A fifth net was set on April 26, a sixth net was set on April 28, and a seventh net was set on April 30, 2018, as ice along the shoreline continued to recede. Portions of the flowage were open for several weeks prior to setting nets but the boat landings were iced in. The City of Oconto Falls Public Works Department graciously assisted in pushing out ice from the East Side boat landing to allow the DNR to launch a boat and begin the survey. Nets were lifted daily from April 26 through May 4, for a total of 54 net nights. All fish captured were identified to species. Gamefish were measured to the nearest 0.1 inch and given a top caudal fin clip (for mark recapture population estimate). Anal fin rays (northern pike) or dorsal spines (walleye, bass) were collected from 5 gamefish per 0.5-inch group per species. Scales or anal spines (yellow perch) were collected from 5 panfish per 0.5-inch group per species. Lengths on at least 250 of each panfish species were taken to the nearest 0.1 inch with the remainder counted. A WDNR standard direct current double anode electrofishing boat was used to sample 3.4 miles of shoreline on the evening of May 22, 2018. All fish were collected for two staggered 0.5 mile transects and only gamefish were collected for the remaining 2.4 miles of shoreline that were sampled (Spring Electrofishing II) per protocol. Fish were measured to the nearest 0.1 inch and gamefish were inspected for a top caudal fin clip. Additional aging structures were collected for length bins not filled during the netting survey. Fish collecting with both gear types (netting and electrofishing) were combined to increase sample sizes for length frequency and age and growth analysis.

RESULTS

Water temperature at the start of the spring netting survey was 44F and rose to 54F by the last day of netting. Due to a record cold and snowy early April3, 2018 was a much later ice-out date on area lakes compared to most years. High flows throughout the survey (Figure 2) created a challenge in finding suitable locations out of the current for fyke nets to be effective. Debris caught in the leads had to be cleaned out daily, and such fouling of the nets may have affected fishability. Discharge recorded at the USGS gauging station upstream at County BB ranged from 1550-2130 cubic feet per second (cfs) during the 2018 survey, compared to 1130-1360 cfs during the 2007 survey. A total of 940 fish (including recaptures) of eighteen different species were collected throughout the survey period (Table 3). Catch per gear type is shown for each species sampled (Tables 4 and 5). Bluegill, black crappie, rock bass, bowfin, northern pike, and smallmouth bass were common.

Found online at https://dnr.wi.gov/topic/fishing/documents/reports/ocontoocontofalls2007.pdf

3 https://weather.com/storms/winter/news/2018-04-16-record-cold-snow-first-half-april

Bluegill Bluegill were the most abundant panfish species captured, with a total of 111 sampled. The catch rate was 1.7/net night and 1/mile for electrofishing (Tables 4 and 5). The catch rate for bluegill in fyke nets was significantly lower than the 2007 survey (35.5/net night). Average length was 5.9 inches with a range from 3.1 to 8.5 inches (Table 3). Size structure is fair, with 48% being 6 inches or greater, but only 3% being at least 8 inches (Figure 3). The largest bluegill was 8.5 inches and estimated at 4 years old. The growth rate of bluegills is better than the 2007 survey and the northeast Wisconsin average. In summary, there are fewer bluegill compared to the 2007 survey, but growth rates have improved (Figure 4), possibly due to lower density. Black Crappie A total of 79 black crappies were sampled, compared to 134 in the 2007 survey. The catch rate was 1.1/net night and 8/mile for electrofishing (Tables 4 and 5). The average length was 9.1 inches with a range from 4.3 to 12.4 inches (Figure 5). Size structure is excellent, with 43% being 10 inches or greater. Multiple age classes were well represented. The mean length at age shows that black crappie in Oconto Falls Pond are growing at similar rates compared to other populations in northeast Wisconsin (Figure 6). Yellow Perch A total of 74 yellow perch were captured, compared to only 8 in the 2007 survey. This increase in numbers may be associated with the later timing of netting in 2018 (late April to early May). Yellow perch typically spawn at 50F, and during the 2018 survey, water temperatures reached 54F. During the 2007 survey, nets were set in late March through April 5 and water temperatures did not exceed 46F during that survey. In 2018, size structure was fair, and average length was 7.3 inches with a range from 3.0 to 10.7 inches (Figure 7). Ages 3 and 4 yellow perch comprised 80% of the catch. In 2012, 5500 yearling yellow perch were stocked in Oconto Falls Pond. Only one fish from that age class was captured during the survey. For younger age classes, yellow perch in Oconto Falls Pond are growing at similar rates or slightly faster than other inland lakes in northeast Wisconsin. For older age classes, yellow perch appear to be growing slower, but low sample sizes for ages 6, 7, and 8 make it difficult to draw conclusions on growth rates of older perch (Figure 8). Northern Pike Northern pike were the dominant predator species captured, with a total of 210 sampled including 46 recaptured individuals. The catch rate for spring fyke netting was 3.1/net night (Table 4). Average length was 19.7 inches with a range from 8.8 to 40.2 inches (Table 3). Size structure was good with 34% of the fish being greater than 21 inches (Figure 9) with multiple age classes contributing. Northern pike growth rates were similar to the northeast Wisconsin average for most ages (Figure 10). It should be noted that scales were used to calculate the northeast Wisconsin averages and with the 2007 survey data while anal fin rays were used for the 2018 survey. Accuracy of age interpretation is somewhat higher with fin rays, particularly for older pike. The population estimate for northern pike was 212 adults (1.2 per acre), with a 95% confidence range between 160 and 287 fish. This estimate is considered a low population density for pike. In comparison, the 2007 population for northern pike was estimated at 312 adults (1.7 per acre), while the 1995 population estimate was 1,657 fish (9.2 per acre)4.

4 Langhurst, R. 1995 survey. Unpublished data in WDNR (Peshtigo Office) files for Oconto Falls Pond.

Largemouth Bass A total of 52 largemouth bass were sampled, including one recaptured individual. The catch rate for spring fyke netting was 0.7/net night and 2/mile for electrofishing (Tables 4 and 5). Average length of largemouth bass was 14.4 inches with a range from 9.2 to 20.5 inches. Size structure was very good with 65% over the 14-inch size minimum (Figure 11). It takes approximately 5 years for a largemouth bass to reach 14 inches in Oconto Falls Pond. Growth rates are generally similar to northeast Wisconsin averages and the 2007 survey (Figure 12). The oldest largemouth bass was 18.8 inches and estimated at age 12. There is steady recruitment of largemouth bass, with nine age classes being represented. A population estimate for largemouth bass was not generated since only one fish was recaptured. Smallmouth Bass A total of 80 smallmouth bass were sampled, including one recaptured individual. The catch rate for spring fyke netting was 0.4/net night and 22.5/mile for electrofishing (Tables 4 and 5). Average length of smallmouth bass was 13.4 inches with a range from 5.8 to 17.5 inches. Size structure was very good with 52% over the 14-inch size minimum (Figure 13). It takes approximately 6 years for a smallmouth bass to reach 14 inches in Oconto Falls Pond. Growth rates are somewhat slower than other lakes in northeast Wisconsin (Figure 14) and could be a factor of higher density of smallmouth bass competing for food resources. There is steady recruitment of smallmouth bass, with eleven year classes being represented. Other Species Other species captured are listed in Table 3 and include from most to least in abundance: bowfin, rock bass, bullhead spp. (brown and yellow), white sucker, common carp, green sunfish, golden shiner, brook trout, walleye, and muskellunge. One 20.8 inch male walleye that was estimated at age 6 was captured. One male 42.1 inch male muskellunge was captured in Net 5 off of the island. That fish did not have any fin clips or tags, but an internal PIT tag was inserted. Neither of these species are stocked and natural reproduction is unlikely in Oconto Falls Pond. It is possible that the walleye and musky migrated downstream from other waterbodies connected to the North Branch Oconto River. A total of 3 mudpuppies, a large salamander species that prefers good water quality, were captured.

DISCUSSION AND RECOMMENDATIONS Oconto Falls Pond is moderately developed with homes and cottages, but large stretches of natural shoreline exist. Native aquatic vegetation such as coontail and wild celery provide good habitat. Stumps and fallen trees provide abundant woody habitat. A recent survey completed of the shoreline recorded coarse woody habitat density as 32 logs per mile5. The 2018 survey captured significantly fewer fish overall than the 2007 survey. Lower catches may have been influenced by high flows and reduced fishability of the nets during the 2018 survey. Additionally, some species, such as bluegill and black crappie, may simply be in lower abundance. Bluegill exhibited faster growth rates compared to the previous survey. This change may suggest that their abundance is reduced, leading to less competition for food resources and corresponding higher growth rates. If catch per effort of bluegill or black crappie remains low in the next survey, a special regulation for panfish may be considered. A variety of special regulations to reduce panfish harvest were enacted in 2016 on approximately 100 lakes throughout Wisconsin. Information on the success of these experimental

5 http://www.co.oconto.wi.us/i_oconto/pu/72f2f4f71245/ocontosummary2018.pdf

regulations will be forthcoming, with most experimental lakes being surveyed in 2019 and 2020. This study may help to inform management on an appropriate panfish regulation for Oconto Falls Pond, if bluegill or black crappie continue to show signs of low abundance. The fishery of Oconto Falls Pond continues to be diverse with good populations of gamefish. Northern pike, smallmouth bass, and largemouth bass continue to be the dominant predators. These gamefish species are providing quality fishing opportunities for anglers. Panfish size structure and growth rates have generally improved. I recommend continuing to manage the flowage for panfish, pike, and bass. Based on the 2018 survey results, I don’t believe that fish stocking is needed. Public access is good for this flowage, so no improvements are suggested at this time. No changes to the general fishing regulation are recommended at this time. The next comprehensive survey for Oconto Falls Pond is scheduled for 2028.

Table 1—Stocking history of Oconto Falls Pond from 1972 to 2018. Year Species Strain Age Class Number

Stocked Avg. Length (in.)

Source

1995 Largemouth Bass Unspecified Fingerling 3,000 3.9 DNR Coop Ponds 2012 Yellow Perch Unspecified Yearling 5,500 5 Private Hatchery 2015 Bluegill Unspecified Yearling 5,000 4 Private Hatchery 2015 Black Crappie Unspecified Yearling 5,000 4 Private Hatchery 2016 Bluegill Unspecified Yearling 5,000 3 Private Hatchery 2016 Black Crappie Unspecified Yearling 5,000 3 Private Hatchery Table 2– WDNR fisheries surveys completed on Oconto Falls Flowage from 1995 to 2018.

Date Survey Type Effort Primary survey purpose

May 22, 2018 Electrofishing 3.4 miles Gamefish/panfish assessment (SEII)

April 25-May 4, 2018 Fyke net 54 net nights Gamefish population estimate & panfish

assessment May 15 & 17,

2007 Electrofishing 3.3 miles LMB assessment

Mar 28-Apr 4, 2007 Fyke net 48 net nights Gamefish population estimate & panfish

assessment

July 5-6, 2006 Mini fyke net 6 net nights Panfish fish community assessment

Sept 12, 2006 Electrofishing 3.3 miles Gamefish/panfish assessment

Mar 26-Apr 14, 1995 Fyke net 88 net nights Gamefish population estimate & panfish

assessment

Table 3. – Total number, percent of total, average length, and length range of fish species captured with all gear types in 2007 and 2018 in Oconto Falls Pond. Numbers include recaptured individuals.

*COMMON NAME OF FISH NUMBER PERCENTAVERAGE LENGTH

LENGTH RANGE(inches) NUMBER PERCENT

AVERAGE LENGTH

LENGTH RANGE(inches)

Black Crappie 134 4.7% 8.2 4.1 - 15.2 79 8.4% 9.1 4.3 - 12.4Bluegill 1706 59.3% 5.2 2.9 - 8.6 111 11.8% 5.9 3.1 - 8.5Largemouth Bass 90 3.1% 14.0 6.5 - 20.5 52 5.5% 14.4 9.2 - 20.5Smallmouth Bass 70 2.4% 12.5 5.3 - 17.3 80 8.5% 13.4 5.8 - 17.5Northern Pike 257 8.9% 19.7 9.5 - 38.9 210 22.3% 19.7 8.8 - 40.2Pumpkinseed 335 11.6% 5.1 3.2 - 9.0 26 2.8% 5.5 3.9 - 7.2Rock Bass 98 3.4% 5.7 3.5 - 9.0 105 11.2% 6.5 4.0 - 9.1Yellow Perch 8 0.3% 6.4 4.5 - 7.6 74 7.9% 7.3 3.0 - 10.7Green Sunfish 1 0.0% 4.2 7 0.7% 5.4 5.3 - 5.4Brook Trout 1 0.0% 12.2 4 0.4% 10.8 9.0 - 13.1Walleye 0 0.0% 1 0.1% 20.8Muskellunge 0 0.0% 1 0.1% 42.1Pumpkinseed x Bluegill 0 0.0% 1 0.1% 5.1Common Carp 24 0.8% 21 2.2%Bullhead spp. 85 3.0% 22 2.3%Bowfin 2 0.1% 118 12.6%White Sucker 48 1.7% 22 2.3%Golden Shiner 18 0.6% 6 0.6%Total 2,877 100.0% 940 100.0%

2007 2018

Table 4. – Catch summary for spring fyke netting in 2007 and 2018 in Oconto Falls Pond. Totals include recaptured individuals.

2018 Spring Fyke Netting

2007 Spring Fyke Netting

(54 net nights) (48 net nights)

Total Catch

per Total Catch

per

Catch net

night Catch net

night Black Crappie 71 1.1 134 2.8 Bluegill 110 1.7 1706 35.5 Largemouth Bass 47 0.7 80 1.7 Smallmouth Bass 26 0.4 11 0.2 Northern Pike 200 3.1 237 4.9 Pumpkinseed 26 0.4 335 7.0 Rock Bass 102 1.6 98 2.0 Yellow Perch 55 0.8 8 0.2 Bullhead Sp. 22 0.3 85 1.8 White Sucker 8 0.1 48 1.0

Table 5. – Catch summary for electrofishing surveys in Oconto Falls Pond in 2007 and 2018. Totals include recaptured individuals.

2018 Spring Electrofishinga

2007 Spring Electrofishingb

22-May-2018 15-May-2007 17-May-2007 Total Catch Total Catch

Catch

per mile Catch

per mile

Largemouth Bass 5 2 10 3.0

Smallmouth Bass 54 22.5 59 17.9

Northern Pike 10 4.2 Black Crappie 8 8 Bluegill 1 1 Rock Bass 3 3 Yellow Perch 19 19 White Sucker 14 14 aGamefish collected for 2.4 miles shoreline. Panfish also collected for two 1/2 mile stations.

bOnly bass collected for 3.3 miles shoreline.

Figure 1. Locations of 7 fyke nets on Oconto Falls Pond, Oconto County, 2018.

Figure 2. Discharge of the Oconto River measured at USGS gauging station at the CTH BB bridge crossing, January 1 – October 17, 2018. Yellow highlighted box indicates the flows during the 2018 survey.

2018 survey

Figure 3. – Bluegill length frequency distribution from Oconto Falls Pond surveys, 2007 and 2018.

Figure 4. – Bluegill mean length at age from Oconto Falls Pond in 2018 and 2007, compared to northeast Wisconsin averages.

Figure 5. – Black crappie length frequency distribution from Oconto Falls Pond surveys, 2007 and 2018.

Figure 6. – Black crappie mean length at age from Oconto Falls Pond in 2018 and 2007, compared to northeast Wisconsin averages.

Figure 7. – Yellow perch length frequency distribution from Oconto Falls Pond surveys, 2007 and 2018.

Figure 8. – Yellow perch mean length at age from Oconto Falls Pond in 2018 and 2007, compared to northeast Wisconsin averages.

Figure 9. – Northern pike length frequency distribution from Oconto Falls Pond surveys, 2007 and 2018.

Figure 10. – Northern pike mean length at age from Oconto Falls Pond in 2018 and 2007, compared to northeast Wisconsin averages.

Figure 11. – Largemouth bass length frequency distribution from Oconto Falls Pond surveys, 2007 and 2018.

Figure 12. – Largemouth bass mean length at age from Oconto Falls Pond in 2018 and 2007, compared to northeast Wisconsin averages.

Figure 13. – Smallmouth bass length frequency distribution from Oconto Falls Pond surveys, 2007 and 2018.

Figure 14. – Smallmouth bass mean length at age from Oconto Falls Pond in 2018 and 2007, compared to northeast Wisconsin averages.

Appendix – Photos

East Side boat landing on April 24, 2018. Notice open water in main flowage, with ice and snow remaining along west shoreline.

Oconto Falls Pond shoreline with a fyke net set in the water.

Ron Rhode and Ben Ewoldt hold northern pike of a size that were commonly caught in the nets. Note the snow and ice on the opposite shoreline.

Four brook trout were caught in the nets and may be the result of stocking upriver.

Three mudpuppies (salamander species) were captured in fyke nets.

Ben Ewoldt holds a 42.1 inch male muskellunge captured in Net 5.