Reproductive Responses of Five White Sucker (Catostomus commersoni) Populations in Relation to Lake Acidity

Abstract

White sucker (Catostomus commersoni) in three acid lakes (pH 4.90, 5.56, and 5.58) frequently matured at older ages and larger sizes and had shorter reproductive life spans than white sucker in two circumneutral lakes (pH 6.30 and 6.35). Reproductive life span was positively correlated in females (r = 0.97) and males (r = 0.85) with lake pH. In the acid lakes, elevated mortality rates coincided with the onset of sexual maturity whereas in circumneutral lakes, mortality rates did not change at maturity. Ovarian weight and ovarian somatic index values were not significantly different between females from two acid and two circumneutral lakes. Values of fecundity, ova dry weight, testicular weight, and testicular somatic index of fish in acid lakes were either significantly greater than or equal to values in white sucker from circumneutral lakes. Results are discussed within the context of life history theory.