Surveillance of viral diseases in free-living turbot (Scophthalmus maeoticus, Pallas, 1814) in the Northern Black Sea and Sea of Azov

Abstract

Purpose. The development of marine aquaculture in the Black Sea is relevant and promising for many reasons, as stated in the decisions and documents of national organizations in the region and the General Fisheries Commission for the Mediterranean (GFCM). Turbot is one of the most valuable fish marketed in seaside countries of the Black Sea as well as in the European Union. Various aspects of the biology of turbot have been investigated yet.Butunfortunately, surveillance procedures for listed diseasesandanalysis of the possibility its prevention and spread have not been provided. Therefore, in this study, in order to evaluate the data on viral diseases of turbot in Ukraine, in 2020 a field survey in free-living Black Sea turbot (Scophthalmus maeoticus) in the northern parts of Black Sea and Sea of Azov was carried out. Methodology. Before sampling all fish were observed for the external lesions, measured from snout to tail length and of total length and weight. Sampling included pooled internal organs, gills and brain. Cell culture and polymerase chain reaction (PCR) methods were used to identify viral diseases. Findings. An external fish examination did not reveal any sign of disease. The internal organs, as well as the gills, were in good condition and had appropriate color, shape and without any pathological changes. All tested samples were free of IPNV, VHSV and VNN viruses as was determined by the methods of cell culture and PCR. The cytopathic effect (CPE) on cells was not observed after the first and the second blind passages. Using the RT-PCR method, we did not identify any of the viruses we were looking for. Originality. This was the first attempt to screen turbot viral diseases in the Ukrainian waters of the Black and Azov Seas. Practical value. In future the permanent surveillance of viral diseases in turbotin accordance with the EU strategy on animal health allows to prevent the outbreaks and develop new approaches for the diagnostic tests in purpose to study the ecology of pathogens in different areas. Key words: turbot, the Black Sea, viral diseases, cell culture, PCR.