This paper is the first report on the occurrence of Atherina boyeri in this region. A total of 103 individuals of A. boyeri were caught with fyke-nets (mesh size: 5 mm, polyamide) in May and June 2022. The length and weight of the sampled fish ranged from 6.52 to 8.57 cm and 1.44 to 3.46 g, respectively. The exponent b of length/weight ratio was calculated as 3.091 indicating that species presented an isometric growth. The mean value of the relative condition factor Kn was calculated as 1.106 ± 0.011. In conclusion, this study provides the first and valuable information about the spatial distribution of A. boyeri and the biodiversity of the new habitat of Reyhanlı Dam Lake. Within the scope of the traceability of a newly formed ecosystem, it would be beneficial to more extensively investigate this species in terms of the food web, population dynamics, etc. Therefore, more studies should be carried out to determine the aquatic biodiversity and population dynamics of the fishery resources in the lake. The results of this study should be considered by local fishery management authorities and decision-makers to ensure the sustainability of fishery resources and to implement appropriate fishery management approaches.
