Walleye Egg Survival during Incubation on Several Types of Bottom in Lake Winnibigoshish, Minnesota, and Connecting Waters

Abstract

Survival of naturally spawned walleye (Stizostedion vitreum vitreum) eggs to pre-hatching stage was determined on five bottom areas of Lake Winnibigoshish, Minnesota, and connecting waters over 4 years. These bottom types included soft muck, sand, gravel, rubble, and boulders. Egg sampling was done at intervals throughout the incubation period and estimates of egg abundance made shortly after the completion of spawning and at or near the eyed-egg stage. Initial fertility of walleye eggs was high (96-100 percent), but the percentage of live eggs declined steadily during incubation. During the eyed-egg stage, however, there was an apparent increase in the percentage survival because of disappearance of dead eggs. Egg survival was best on gravel-rubble, both as percentage survival and numbers of eggs surviving the eyed stage. Survival of eggs on improved gravel-rubble bottom was as high as 35.7 percent but on muck bottom was as low as 0.6 percent. Survival on better bottoms of gravel and rubble averaged 25 percent. Abundance of eggs on sand bottom to which gravel and rubble had been added was more than 10 times that observed previously, and survival of eggs on the improved bottom increased fivefold. Length of incubation period, which was determined by water temperature, was a factor in egg survival. Walleyes selected gravel bottom for spawning when it was available, and most eggs were deposited in water from 12 to 30 inches deep. Low water levels in the spring of 1958 made much former spawning area unavailable and may have been a factor in a weak 1958 year class.