Nemipterus randalli Russell, 1986 was first recorded from the Israel coast in 2006. Since then, the species has successfully been established in the Eastern Mediterranean seas and is commercially important in the Mediterranean Sea. In this study, the genetic structure of N. randalli populations was investigated with the COI gene region with population parameters from the Iskenderun, Mersin and Antalya Bays on the coast of Turkey. A total of 582 bp of partial COI sequences were obtained after alignment. The average nucleotide composition of thymine (T), cytosine (C), adenine (A), and guanine (G) were 33.2%, 26.6%, 22.6% and 17.6%, respectively. The analysis of the COI region revealed 14 different haplotypes, and haplotype diversity within populations was found to Antalya, 0.4833, Mersin, 0.6733 and Iskenderun, 0.5533. The mean haplotype diversity between populations was 0.8310. The highest genetic differentiation was between Iskenderun and Antalya populations (0.00524). Length-weight relationships were separately evaluated for each population of all individuals. The exponent b demonstrated positive allometric growth. The length-weight relationships were calculated for Iskenderun, Mersin and Antalya populations of all individuals as W=0.0059 x L3.2887 (r2 = 0.9780), W=0.0054 x L3.3281 (r2 =0.9816), W= 0.0077 x L3.1975 (r2 =0.9802), respectively. The b value in the length-weight relationship showed that a positive allometric growth type was obtained from all the sampled three populations. This study supplies the first fishery information about the genetic structure and biological characteristics of N. randalli populations from the coasts of Turkey. The results obtained from genetic analysis and biological parameters support each other and can support future studies. Keywords: Randall’s threadfin bream, Nemi

Randall’s threadfin bream, Nemipterus randalli, mtDNA, COI gene, length-weight relationships, Turkey