Conesus Lake Fish Stock Assessments 2001-2009

Abstract

Warm water fisheries assessments using standard gangs of gill nets were conducted in Conesus Lake in September of 2001, 2004, and 2009. The purpose of the surveys was to assess the fish community; the contribution of stocked fingerlings to the walleye (Sander vitreus) population; estimate population characteristics of walleye, smallmouth bass (Micropterus dolomieui), and northern pike (Esox lucius); compare fish community structure to previous surveys; and guide the development of appropriate management recommendations. From the 1990’s to the 2000’s, species dominance shifted from walleye to sunfish (Lepomis, sp.), and yellow perch (Perca flavescens) went from being a major component of the fish community in 1991 to a minor component in 1997, to nearly absent in 2004. Brown bullhead (Ameirus nebulosus) became an increasingly larger component of the fish community in the 2000’s. The walleye population during the 2000’s had an abundance of larger, older fish in excellent condition. Despite extensive migratory spawning runs in the inlet streams that could be producing fry that potentially recruit to adults, the walleye population is mainly sustained by stocked fingerlings. While they are growing slower than in the 1990’s, survival and recruitment of the stocked fingerlings remains good. Slower growth and lower condition could be a sign that the alewife population in Conesus Lake is declining, but no definitive statement regarding the alewife population can be made until further hydroacoustic surveys of the forage community are conducted. Because of discrepancies of scale ages among readers, walleye age and growth analyses for these surveys should be viewed cautiously, and otoliths should be used to age walleye in future surveys. The fishing quality for Conesus Lake walleyes should remain very good for several years. The smallmouth bass population by 2009 had an abundance of larger, older fish in fair condition. The 2007 and 2006 year classes appear to be strong, but individual fish of these year classes may grow slowly and be in less than desirable condition. The fishing quality for Conesus Lake smallmouths should remain good for several years as the fish from these year classes mature and grow. Northern pike appear to be moderately abundant. The recent maintenance of appropriate lake water levels during early spring have provided adequate flooding of constructed marshes in the Conesus Inlet Wildlife Management Area. This appears to have resulted in successful spawning, fry production, survival, and recruitment of northern pike. Adult pike, while fast growing, are in below average condition in Conesus Lake. The yellow perch decline in abundance following a late 1970’s alewife (Alosa pseudoharengus) invasion continued during the 1991- 1997 period and remained at this low level from 2001 to 2009. Alewife gill net CPUE varied greatly from 1985 to 2001 and remained at a consistent low level since 2001. While relatively large, yellow perch are in poor condition and alewives are smaller than average and in poor condition. Rock bass (Ambloplites rupestris) and bluegill (Lepomis macrochirus) relative abundance doubled from 2001 to 2009, while pumpkinseed (Lepomis gibbosus) abundance showed little change. Survival and growth appears to be consistent for all three species. Growth was above average for all three species, but condition was poor for rock bass and moderately poor for pumpkinseed and bluegill. Rock bass size structure was poor and few preferred sized 2 pumpkinseeds and bluegills were sampled. Size quality in bluegills declined from 1991-1997 levels. It is recommended that all current management actions be continued, 50 day walleye fingerlings be stocked annually over five years, the success of stocked 50 day walleye fingerlings be evaluated, and new objectives be developed in a revised Conesus Lake fisheries management plan.