Angling Characteristics and Vital Statistics of Fish Populations in Long Lake, Fond Du Lac County, Wisconsin
Scheirer, Jeffrey Wm.
University of Wisconsin-Stevens Point, College of Natural Resources
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We used fyke netting, electrofishing, tagged fish, and a creel survey to evaluate the angling characteristics and vital statistics of northern pike (Esox lucius), largemouth bass (Micropterus salmoides), walleye (Stizostedion vitreum), bluegill (Lepomis macrochirus), pumpkinseed (Lepomis gibbosus), yellow perch (Perea flavescens), black crappie (Pomoxis nigromaculatus), rock bass (Ambloplites rupestris), and bullhead (Ictalurus sp.) populations in 185-hectare Long Lake in Fond du Lac County, Wisconsin in 1986 - 87. The fyke nets selected the larger fish of most species, except bluegills. Estimated fishing pressure was 1.33 hrs/ha/day for the period May 3, 1986 - May 1, 1987 and 2.79 hrs/ha/day from May 3 - August 31, 1986. Monthly fishing pressure peaked in May and February. Monthly harvest rates ranged from 0 to 406 fish/100 hours of angling. The estimated annual harvest included 2,186 northern pike, 1,498 largemouth bass, 330 walleyes, 53,709 bluegills, 8,235 yellow perch, 4,936 black crappies, and 2,529 pumpkinseeds. Proportional Stock Densities (PSD) for largemouth bass and bluegills captured by electrofishing in spring were 69 and 34%, respectively. Weighted predator and prey PSD fell in the optimal area formed by intersecting objective ranges for predators and prey. Relative weights (Wr ) of largemouth bass, bluegills and black crappies were satisfactory, but Wr of walleyes was below the recommended range. Northern pike in Long Lake weighed less for their length than pike from Michigan lakes. Floy tags did not affect the condition of tagged northern pike, but tagged pike grew slower than untagged pike. I found differences between ages -of northern pike determined from scales and cleithra from the same fish and descrepancies in number of annuli on scales taken from tagged pike in successive years. Largemouth bass, bluegills, pumpkinseeds, rock bass, and black crappies grew at an average rate, but northern pike and yellow perch grew slower than those statewide. Petersen estimates of population size were 40.1, 43.6, and 25.2 fish/ha and exploitation rates, determined from tag returns, were 18, 27, and 7% for largemouth bass of 250 mm or longer, and northern pike and walleyes 381 mm long or longer, respectively. Annual mortality rates from catch curves were 42, 63, 73, 73, 69, 55, and 59% for largemouth bass, northern pike, bluegills, black crappies, pumpkinseeds, rock bass, and yellow perch, respectively. The estimated total annual mortality rates for bluegills and black crappies were high and exploitation of largemouth bass and walleyes, low in comparison with other populations. Fish and crayfish (Orconectes sp.) were the main food items in of 16 of 25 stomachs from largemouth bass captured by angling and electrofishing.