Walleye Growth in Relation to Alewife Abundance in Otsego Lake, New York

Walleyes (Sander vitreus) were stocked into Otsego Lake, NY in 2000 to control alewives (Alosa pseudoharengus), which had been illegally introduced in 1986. In Otsego Lake, alewives quickly became the primary food of walleyes. Alewife populations underwent massive fluctuations before plummeting to close to zero in recent years. This study was conducted to determine if the fluctuating alewife population density impacted the growth of various life stages and year classes of walleye. A backpack electrofisher was used to collect walleye on their spawning run in tributary streams and a boat electrofisher was used to collect walleye from their staging area in the lake around Sunken Island. From 2008 to present, over 400 walleye were sexed, measured and scales removed for aging. Back calculation of size at age was used to determine growth of various size and year classes and compared to hydroacoustic data on alewife abundance. From the initial stocking, there was a steady decline in walleye growth in all age classes until 2003, then a steady increase in walleye growth to the present. Walleye growth was not correlated with alewife abundance. Thus walleye growth rates have not been hindered by the collapse of the alewife population.