TY - JOUR T1 - Photobacteriosis in farmed Atlantic bluefin tuna (Thunnus thynnus): The first comprehensive study of the Aegean Sea TT - Yetiştiricilikte Atlantik mavi yüzgeçli orkinosunda (Thunnus thynnus) fotobakteriyozis: Ege Denizi’ne ait ilk kapsamlı çalışma AU - Dinçtürk, Ezgi AU - Tanrıkul, Tansel PY - 2026 DA - June Y2 - 2026 DO - 10.12714/egejfas.43.3.06 JF - Ege Journal of Fisheries and Aquatic Sciences JO - EgeJFAS PB - Ege Üniversitesi WT - DergiPark SN - 2148-3140 SP - 233 EP - 240 VL - 43 IS - 3 LA - en AB - Photobacterium damselae subsp. damselae is a significant pathogen that cause severe bacterial septicemia in a broad range of hosts. This study presents the first comprehensive analysis of Photobacterium damselae subsp. damselae affecting farmed Atlantic bluefin tuna (Thunnus thynnus) stocks in Aegean Sea, Türkiye. The total mortality rate of the farm was calculated as 18% exhibiting clinical signs of the disease, characterised by lethargic swimming and loss of equilibrium in bluefin tuna cages. Although external clinical signs were not determined, hemorrhages were observed in liver, swim bladder and heart. Microbiological examinations resulted in the isolation of a total of four bacterial strains, including two isolates from the summer sampling period and two isolates from the autumn sampling period. Among these, representative strains designated as THAS1 and THAS2 were selected for further biochemical and molecular characterization, through which Photobacterium damselae subsp. damselae was identified. Histopathological examinations of liver, heart, spleen, and kidney tissues associated with the infection revealed the presence of melanomacrophage centers in histological sections of the spleen and kidney. Consequently, this study reveals the epizootic and impact of P. d. subsp. damselae infection in farmed Atlantic bluefin tuna with clinical and microbiological results associated with pathological changes. Further research on the epidemiology and epizootiology of this disease is essential for sustainable aquaculture of tuna fish stocks, especially in Mediterranean. KW - Photobacterium KW - marine cage culture KW - tuna KW - bacteriology KW - histopathology N2 - Photobacterium damselae subsp. damselae, birçok deniz balığı türünde şiddetli bakteriyel septisemiye neden olan önemli bir patojendir. Bu çalışma, Türkiye’nin Ege Denizi’nde yetiştiriciliği yapılan Atlantik mavi yüzgeçli orkinos (Thunnus thynnus) stoklarını etkileyen Photobacterium damselae subsp. damselae’nin ilk kapsamlı analizini sunmaktadır. Hastalığa ait klinik bulguların gözlendiği işletmede toplam mortalite oranı %18 olarak hesaplanmış olup, mavi yüzgeçli orkinos kafeslerinde letarjik yüzme davranışı ve denge kaybı ile karakterize edilmiştir. Dış bakıda klinik bulgular tespit edilmemekle birlikte, karaciğer, yüzme kesesi ve kalpte hemorajiler gözlenmiştir. Mikrobiyolojik incelemeler sonucunda, yaz örnekleme döneminden iki ve sonbahar örnekleme döneminden iki olmak üzere toplam dört bakteriyel suş izole edilmiştir. Bunlar arasından THAS1 ve THAS2 olarak adlandırılan temsilci suşlar ileri biyokimyasal ve moleküler karakterizasyon analizleri için seçilmiş ve bu analizler sonucunda Photobacterium damselae subsp. damselae tanımlanmıştır. Enfeksiyonla ilişkili olarak karaciğer, kalp, dalak ve böbrek dokularında yapılan histopatolojik incelemelerde, dalak ve böbreğe ait histolojik kesitlerde melanomakrofaj merkezlerinin varlığı ortaya konulmuştur.Sonuç olarak bu çalışma, yetiştiriciliği yapılan Atlantik mavi yüzgeçli orkinoslarda P. d.subsp. damselae enfeksiyonunun epizootik seyri ve etkilerini, klinik ve mikrobiyolojik bulgular ile patolojik değişiklikler eşliğinde ortaya koymaktadır. Özellikle Akdeniz bölgesinde orkinos yetiştiriciliğinin sürdürülebilirliği açısından, bu hastalığın epidemiyolojisi ve epizootiyolojisine yönelik ileri araştırmalar büyük önem taşımaktadır. CR - Alolod, G.A.L., Matsumoto, S., Koiwai, K., Kondo, H., & Hirono, I. (2024). First report of white muscle disease caused by Photobacterium damselae subsp. damselae in Kuruma shrimp (Penaeus japonicus). Aquaculture, 593, 741278. https://doi.org/10.1016/j.aquaculture.2024.741278 CR - Austin, B., & Austin, D.A. (2016). 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