Our epizootiological survey was focused on bacterial diseases of European sea bass, Dicentrarchus labrax L., an important Mediterranean species for aquaculture, in Greece. Vibriosis and Photobacteriosis were the most severe bacterial diseases, located in the majority of Greek mariculture areas (Argolikos gulf, North Evoic gulf Maliakos gulf and Thesprotia Sagiada coast, Amvrakikos gulf, Aitoloakarnania Mitikas coast, Ionian island coasts) during the period 1998-2013. A database of 152 cases was formulated, from which 134 cases concerned vibriosis and photobacteriosis, while the rest outbreaks were motile aeromonas septicemia and tenacibaculosis. PCA pointed out three principal components with the following ranking order: a) temperature and seasonality, b) group of mariculture areas and average body weight, and c) case year. The results of logistic analysis showed the temperature - seasonality as the first, in ranking, and the only statistically significant epizootiolological risk factor. Contrast Test (low vs. high temperature values) also proved the significant effect of temperature (p<0.05). Vibriosis pathogen Listonella (Vibrio) anguillarum was recorded in a wide temperature range (12-260°) in the most of Greek rearing locations. In contrast, Vibriosis from rest vibria was found to a narrow temperature range, especially in Argolikos gulf, North Evoic gulf and Ionian Island coasts. Specifically, V. harveyi cases emerged at high temperatures (19-220°C), while those of V. alginolyticus and V. splendidus II at low temperatures (15-170°C). Photobacterium damselae subspecies piscicida in most of Greek rearing areas and Photobacterium damselae subspecies damselae in Argolikos gulf, North Evoic gulf and Ionian Island coasts appeared in a relatively wide range (19-250°C). However, they showed higher frequencies in warm period. The results will support an evolutionary epizootiological survey and will reinforce a preventive biosecurity program in Greek mariculture taking into consideration the temperature - seasonality factor along with the classical sanitary approach.