WISCONSIN DEPARTMENT OF NATURAL RESOURCES FISH MANAGEMENT ACTIVITIES DELAVAN LAKE SPRING 212 Electrofishing and fyke net surveys were conducted on Delavan Lake March 2-May 3, 212. Fyke netting and electrofishing was done primarily in areas providing muskellunge and largemouth bass spawning habitat, although the entire shoreline was electrofished on selected dates. The purpose of these surveys was to collect relative abundance, and size structure information on spawning populations of muskellunge, largemouth bass, walleye, and northern pike. Data was also collected on bluegill and black crappie. Total fyke net sampling effort included 44 net nights for walleye and northern pike, and 6 net nights for muskellunge. Total electrofishing effort was 31.8 miles of shoreline (16.1 hours) for bass, 2 miles of shoreline (1 hour) for walleye and northern pike, and 4 miles (2 hours) for panfish. All walleye, bass, northern pike, and musky collected during the surveys were counted, measured, weighed, and released. Panfish were counted, measured, and released. Largemouth bass were also marked with an upper caudal finclip in order to estimate the number of adult bass in the population (Peterson Population Estimate). Water temperatures ranged between 48 F - 67 F and water clarity was clear to turbid. Results of the fish surveys are recorded in the following tables, graphs, and narrative. Fyke Net Survey (3-27-12 thru 4--12) Table 1. Catch and size data for walleye, northern pike, and muskellunge collected from Delavan Lake during the spring, 212 fyke net survey. CPUE is in number per net night and length data is in inches. SPECIES CPUE MEAN LENGTH MODE RANGE PSD RSD- P RSD- M WALLEYE 3.7 19. 18-18.9 16.1-1 31 6 27. WALLEYE 3.1 17. 17-17.9 12.8-91 1 27. NORTHERN 1.2 26.7 26-29 17.3-1 87 46 PIKE 36.7 NORTHERN 3.2 22.3 2-21.9 14.1-66 6 PIKE 31. MUSKELLUNGE.4 34.4 32.4-36.4
Figure 1. Size distribution of walleye collected from Delavan Lake during the spring, 212 fyke net survey. Female Walleye Numaber Caught 4 4 3 3 2 2 1 1 12 13 14 1 16 17 18 19 2 21 22 23 24 2 26 27 Male Walleye Number Caught 4 4 3 3 2 2 1 1 12 13 14 1 16 17 18 19 2 21 22 23 24 2 26 27
Figure 2. Size distribution of northern pike collected from Delavan Lake during the spring, 212 fyke net survey. Female Northern Pike 6 4 Number Caught 3 2 1 14 1 16 17 18 19 2 21 22 23 24 2 26 27 28 29 3 31 32 33 34 3 36 Male Northern Pike 2 2 Number Caught 1 1 14 1 16 17 18 19 2 21 22 23 24 2 26 27 28 29 3 31 32 33 34 3 36
Walleye Fyke net surveys produced 164 female walleyes for a catch rate of 3.7 per net night, and 136 males for a catch rate of 3.1 per net night. Most of the females were between 18. and 18.9 inches long and the average length was 19. inches. Most of the males were between 17. and 17.9 inches long and averaged 17. inches. PSD (proportional stock density-quality), RSD-P (relative stock density-preferred), and RSD-M (relative stock density-memorable) is the percentage of fish of a designated length group in a sample, and these values were used to assess the overall size structure of the population. Size structure of Delavan Lake walleyes was excellent as indicated by robust PSD, RSD-P, and RSD-M values. 74% of the females and 22% of the males in the sample were larger than the minimum size limit of 18 inches. Several year classes of adult walleyes were present in the lake as indicated by the wide range in lengths of both females and males. Northern Pike Fifty two female and 14 male northern pike were collected during fyke netting for catch rates of 1.2 and 3.2 per net night respectively. Most of the females were between 26 and 29 inches long and the average length was 26.7 inches. The largest female was 36.7 inches long. Most of the males were between 2. and 21.9 inches long and averaged 22.3 inches. Size structure for Delavan Lake northern pike was excellent as indicated by the high PSD, RSD-P, and RSD-M values. 12% of the females in the sample were larger than the minimum size limit of 32 inches. The largest male in the sample was 31. inches long. Delavan Lake supports several year classes of northern pike. Muskellunge Only two male muskellunge were collected and they were 32.4 and 36.4 inches long.
Electrofishing Surveys (3-2-12 thru -3-12 Table 2. Catch and size data for bluegill, black crappie, walleye, largemouth bass, and northern pike collected from Delavan Lake during the spring, 212 electrofishing surveys. CPUE is in number per mile and length data is in inches. SPECIES CPUE MEAN MODE RANGE PSD RSD-P LENGTH BLUEGILL 27 7.1 6.-7. 4.-9. 89 22 BLACK 9 9.9 1 7.-11.7 97 7 CRAPPIE WALLEYE 6. 19.2 18.- 16.8-22.8 18.9 WALLEYE 67 17.7 18.- 13.7-21.3 9 3 18.9 LARGEMOUTH 49.3 1.4 16.- 6.7-2.4 92 66 BASS 17.9 NORTHERN PIKE 6 22.9 27.- 29. 14.8-29. Figure 3. Size distribution of bluegill and black crappie collected from Delavan Lake during spring, 212 electrofishing surveys. Bluegill Black Crappie 3 3 18 16 14 2 12 N umbe r C a ught 2 1 1 N u mb e r C a u g h t 1 8 6 4 2 4 6 7 8 9 4 6 7 8 9 1 11 Le ngt h i n I nc he s L e n g t h i n I n c h e s
Figure 4. Size distribution of largemouth bass collected from Delavan Lake during spring, 212 electrofishing surveys. Largemouth Bass Number Caught 1 9 8 7 6 4 3 2 1 6 7 8 9 1 11 12 13 14 1 16 17 18 19 2 Figure. Size distribution for walleyes collected from Delavan Lake during spring, 212 electrofishing surveys. Male Walleye Number Caught 4 3 3 2 2 1 1 13 14 1 16 17 18 19 2 21 Bluegill Electrofishing surveys produced 88 bluegills for a catch rate of 22 per mile. Most of the bluegills were between 6 and 7 inches long and the average length was 7.1 inches. The largest bluegills in the sample were 9 inches long. PSD and RSD-P values were strong and indicated excellent size structure. Several year classes were present.
Black Crappie 37 black crappie were collected by electrofishing for a catch rate of 9 per mile. Several year classes were represented. Most of the crappies in the sample were 1 inches long and the largest crappie was 11.7 inches long. The average length was 9.9 inches. Size structure was excellent with robust PSD and RSD-P values. Largemouth Bass 1,37 largemouth bass were collected during electrofishing surveys for a catch rate of 49.3 per mile. All of these fish were marked with an upper caudal finclip. 491 bass were measured. Several year classes were present and the average length was 1.4 inches. Most bass were between 16 and 17.9 inches long. The largest bass was 2.4 inches long. PSD and RSD-P values were very good and indicated excellent size structure. 14% of the bass in the sample were greater than or equal to the minimum size limit of 18 inches. Largemouth bass abundance was estimated at 6,492 or 3.1 adults per acre. Walleye 134 male walleyes were collected by electrofishing for a catch rate of 67 per mile. Several year classes were represented and length data was similar to length data collected during fyke netting. 48.% of the male walleyes were larger than the minimum size limit of 18 inches. Thirteen females were collected for a catch rate of 6. per mile. Length data on females captured via electrofishing was similar to length data collected during fyke netting. Northern Pike Twelve northern pike were collected by electrofishing for a catch rate of 6 per mile. Length data was similar to length data from fyke netting, although most of the northern pike in the electrofishing sample were larger than northern pike from the fyke net sample. Muskellunge One muskellunge was collected by electrofishing and it was 33.2 inches long. Several other muskellunge were observed but were able to avoid being captured. Fish Stocking
Delavan Lake was stocked with 4,144 large fingerling muskellunge in 211. The stocking quota for 212 is 72,2 small fingerling walleye. Walleye are usually stocked in June. Hatchery Production Walleye reproductive products are collected annually from Delavan Lake and are used to restock Delavan Lake and other lakes in southern Wisconsin. 66 quarts of eggs (about 7.2 million eggs) were collected in spring, 212. Douglas Welch WDNR Fisheries Biologist (262)884-2364