THE COMPARATIVE ANALYSIS OF FISH RESOURCES IN THE DANUBE NEAR BRAILA, WITHIN THE PERIODS 1972-1986 AND 2006-2008
The purpose of this paper is to propose a new indicators for assessing the health of fish population in the Danube River, near Braila. In this way we analyzed the available data sets provided by industrial fishing from this area, for two different periods: present period (2006-2008) and previous period (1972-1986). Between 1972-1986 the environmental conditions in the Danube River were highly affected by direct and indirect anthropogenic activities. In 2006-2008 the human impact on fish populations was diminished because fishing was banned in floodplain areas, economic activities decreased and new legislation on environmental protection came into force. The proposed indicators describing the status of the freshwater fish community from the Danube River, near Braila are: (1) the total capture (TC, tonnes/year); (2) the total capture per unit area (TCA, tonnes/year x km2); (3) the total number of fish species (TNF, number of species/year); (4) the number of valuable fish species (NVF, number of species/year); (5) the number of ruling fish species (NRF, number of species/year); (6) the abundance of flow preference guilds (AFPG , % / guild). This comparative analysis highlights a highly unbalanced structure of the fish community in both periods, but in 2006-2008 the fish community structure come out to be in a changing process due to increase of rheophilic species.