The Walleye Population and Fishery in the Red Cedar River, Wisconsin

Abstract

Walleye, Stizostedion vitreum (Mitchill), were tagged and a partial creel survey conducted in a 12.5 ha segment of the Red Cedar River, Wisconsin, between the impoundments of Tainter Lake and Lake Menomin. Tag returns and electrofishing catches indicated a high concentration of walleye in the river during April and early May. Walleye migrated downstream into Lake Menomin during summer and upstream in fall. Fish was the most important food item and comprised 84 percent of the total food volume of walleye less than 200 mm long and 97 percent of the total for those larger than 200 mm. Total lengths at annulus formation based on the sum of mean annual increments for each year class were 162, 264, 328, 373, 419, 452, 474, 490, 514, 537, 562, and 618 mm for ages I through XII, respectively. Total annual mortality rate determined from catch curves and angler recapture of tagged fish was estimated to be 50 percent for ages II through IX. Exploitation rate, estimated from angler tag returns corrected for nonresponse and tag shedding, was 31 percent for 1973 and 1974. Anglers fished an estimated 273 and 278 hrs/ha, caught 22 and 12 walleye/ha (9.1 and 4.7 kg/ha) at rates of 7 and 4 fish/100 hrs in 1973 and 1974. Mean length of walleye creeled was 362 and 351 mm in 1973 and 1974, and 82 percent of the catch was made up of ages II through V. Males and females appeared to be equally vulnerable to anglers. Population estimates, calculated from creel survey data, ranged from 7.6 to 9.7 walleye/ha and 3.0 to 3.2 kg/ha with a mean of 8.5 walleye/ha (3.1 kg/ha) for walleye 250 mm and longer. Critical size, the size at which a year class reaches its maximum biomass, was estimated to be between 419 and 452 mm total length, weights of 663 and 845 grams, or ages V and VI. Calculation of equilibrium yield per unit recruitment indicated that weight harvested could be increased by 27, 38, and 35 percent with 328, 373, and 419 mm length limits.