Distribution of the critically endangered fan mussel Pinna nobilis population in the Çanakkale Strait and Marmara Sea

This study was conducted with the primary objective of determining the presence of both healthy and impacted Pinna nobilis populations along the European coasts of the Sea of Marmara, followed by the identification of P. nobilis abundance and survival rates in the region encompassing the Çanakkale Strait and the southern coasts of the Sea of Marmara. Underwater surveys were randomly conducted at 19 distinct stations, including 8 stations along the European coasts of the Sea of Marmara, 7 stations along the southern coasts of the Sea of Marmara, and 6 stations within the Çanakkale Strait. SCUBA diving equipment was utilized to record information on habitat structure, water temperature, depth, and visibility at each station. The transect length during underwater surveys and the number of transects at each station were determined based on the condition of the seabed and the size of the area, respectively. Throughout the study period (September 2021 and October 2023), water temperature fluctuated between 17.5°C and 26.6°C. At the end of the study, a total of 395 individuals (147 live, 248 dead) were observed, with live individuals exhibiting total lengths ranging from 16.4 cm to 50.9 cm. This study represents the first investigation into the spatial distribution of P. nobilis along the European coast of the Marmara Sea. The study contributes significantly to enhancing our understanding of the ecology of P. nobilis populations in both the Sea of Marmara and the Çanakkale Strait. Additionally, recommendations for the rehabilitation of impacted populations and the conservation of healthy populations have been provided for decision-makers and fisheries managers.