Short communication Growth and reproduction of largemouth bass Micropterus salmoides Lace Âpe Áde, 1802) in Lake Trasimeno Umbria, Italy) Massimo Lorenzoni * , A.J. Martin Do Èrr, Rocco Erra, Giancarlo Giovinazzo, Mario Mearelli, Sabrina Selvi Dipartimento di Biologia Animale ed Ecologia, Universita Á degli Studi di Perugia, Via Elce di Sotto, 06100 Perugia, Italy Received 27 March 2000; received in revised form 11 September 2000; accepted 11 April 2001 Abstract Growth and reproductive biology of largemouth bass was investigated to study aspects of its biology as well as possible effects upon other ®sh 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 signi®cant 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 1  46:88, K  0:33 and t 0  0:056 for the females and L 1  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. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Micropterus salmoides; Largemouth bass; Growth; Biology; Lake Trasimeno 1. Introduction Largemouth bass Micropterus salmoides Lace Âpe Áde, 1802), a ®sh native to the south-eastern United States, which prefers marshy environments and the shallow waters of larger lakes Hickley et al., 1994). Because it is a premium sport ®sh, it has been introduced, although not always successfully, into several coun- tries in temperate and tropical climates Heidinger, 1976). Largemouth bass were introduced into the Italian inland waters at the end of the last century Alessio, 1981) and spread rapidly throughout the country. It was ®rst recorded in Lake Trasimeno at the end of the 1980s Natali, 1989). It was introduced by sport ®shermen because it is a prized catch but professional ®shermen have also bene®ted from its presence. In 1989, largemouth bass were included in the ®shing statistics with a total catch of about 170 kg, andthisvaluehasincreasedsteadilyeachyear.Fishing hasalwaysbeenoneofthemaineconomicactivitiesof the Lake Trasimeno area having the largest nucleus of professional ®shermen in inland Italy Natali, 1989). Fisheries Research 56 2002) 89±95 * Corresponding author. Tel.: 39-75-5855716; fax: 39-75-5855733. E-mail address: lorenzon@unipg.it M. Lorenzoni). 0165-7836/02/$ ± see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0165-783601)00309-5