Notes on the Fish Fauna Composition of Mesta (Nestos) River in Regard to Management and Conservation

Nestos or Mesta is a trans-boundary river, which flows approximately half in Bulgarian and half in Greek territory. It is the median of the three North Aegean Rivers raised in Bulgaria and it possess the higher watershed in this country. In the current paper it is given a description of the freshwater fish species composition in the system from its source to the estuary and its alterations for a period of almost seventy years. Twenty seven freshwater fish species in total including the European eel Anguilla anguilla L. 1758 are found inhabiting the river system. The number of the discovered non-native limnophilic species increases in time on account of the native rheophilic ones due to anthropogenic changes, mainly microhabitat destruction and introductions.