Growth and reproduction of largemouth bass (Micropterus salmoides Lacepede, 1802) in Lake Trasimeno (Umbria, Italy)

摘要

Growth and reproductive biology of largemouth bass was investigated to study aspects of its biology as well as possible effects upon other fish species as a result of its introduction to Lake Trasimeno. From April 1993 to May 1994, 182 specimens (87 males, 83 females, 12 sexually indeterminate) distributed among seven age classes were captured. The length-weight regression was W = 0.00988LT(3.1512+/-0.027) (males) and W = 0.00888LT(3.184+/-0.032) (females) without any significant differences between sexes. The growth of the 1+age-class is not continuous throughout the year; it slows to almost nothing in the winter, The parameters of the von Bertalanffy growth curve for length were L-infinity = 46.88, K = 0.33 and t(0) = 0.056 for the females and L-infinity = 39.4, K = 0.42 and t(0) = 0.019 for the males. The condition factor indicates that the Lake Trasimeno population is in excellent condition. Reproduction occurs mostly in May. Sexual maturity is reached at 2 years for males and 3 years for females, at lengths and weights of 22 cm and 160 g for males and 30 cm and 397 g for females, respectively. Largemouth bass has adapted well to Lake Trasimeno where physical and trophic conditions favour growth and reproduction.