Osservazioni preliminari sull'introduzione del persico trota (Micropterus salmoides, Lacépède 1802) nel Lago di Bracciano (Lazio).

The black bass is a native Centrarchidae of North America introduced in North Europe at the end of 1800, and reported for the first time in Italy at the beginning of 20th century. It has been recorded in Lake Bracciano (north of Rome) 5 years ago. To evaluate the status of the population of black bass in Lake Bracciano, a study on the ecology of this species was carried on, using 100 individuals. The specimens were aged and sexed and every individual was measured and weighed. Then gonads were taken, weighed and utilized for histological analysis. The absence of individuals older than 2 years could mean adults to have a different behaviour. Maybe they could stay in deep water for a very long period and go near the bank during the breeding period. The relative abundance of young individuals could mean a good status of the population of M. salmoides, that seems well acclimatized. Further and accurate studies on the black bass can contribute for managing the biodiversity of Lake Bracciano for a sustainable conservation of the icthyofuana.