Effects of Ambient Light Variations on Behavior of Yearling, Subadult, and Adult Walleyes (<i>Stizostedion vitreum vitreum</i>)

Abstract

All facts when ordered and synthesized with previously published information suggest that light is the principal abiotic controlling variable of the environment that determines temporal and spatial dimensions of feeding and reproduction in the walleye, Stizostedion vitreum vitreum. Underwater observations during the day revealed that adult walleyes were active in turbid regions of a lake but rested in contact with the substrate in clear-water regions. In the latter instance physical shelter served to shield the eyes of the walleyes from the ambient light. An inverse relation was noted between numbers of walleyes sighted per hour of transect swum and transparency levels of the water. In experimental angling during the open-water season, the total number of walleyes captured and the catch per unit of effort were positively related to illuminance levels. Winter angling through the ice showed a similar relationship, though at percentage light transmission levels one order of magnitude lower. Percentages of walleyes captured per [Formula: see text] increment during openwater at dusk were positively related to percentage decrease in illuminance for the same time intervals and inversely related to absolute levels of illuminance. Other authors have determined that nuptial activity also, and hence reproduction, is governed by variations in the ambient light regime. Key words: Stizostedion vitreum vitreum, walleye, light, behavior, photopic vision, tapetum lucidum, turbidity, preferred habitat, scotopic vision, feeding pattern