Age Structure and Growth Dynamics of European Chub, Squalius cephalus, Linnaeus 1758 (Actinpterygii: Cyprinidae) from two Catchments in Transylvania-Romania

In recent years, research on water monitoring involves more and more the analysis of ichtyofauna in many aspects such as: the number of fish species, their distribution in the catchment sectors, the ratio between them, the dominant species, and growth dynamics and age structure of fish populations.  The chub ( Squalius cephalus ), is in this case an indicator species. It is present in most rivers in Romania and it is well represented numerically. The specimens for our study were collected from the Someșul Mic River (Cluj County) respectively TA¢rnava (Alba County). Growth dynamics in this case is a comparison tool, perfect for fish populations. Age category distribution from the catchments taken into study is also a tool that gives us important information. The absence of some age categories is a question mark related to environmental accidents that occurred on a river or river sector. Through this study, we intend to demonstrate that growth dynamics and age structure are effective tools for characterizing and comparing fish populations.