The complete mitochondrial genome characterization of Thunnus obesus (Scombriformes: Scombridae) and phylogenetic analyses of Thunnus

Thunnu obesus is important in commercial fisheries around the world. Due to human overfishing, climate change and ocean acidification, it was listed as Vulnerable (VU) under the International Union for the Conservation of Nature. In the present study, the complete mitogenome of T. obesus was determined. It is 16,524 bp in length and contains 13 protein-coding genes, 22 tRNA genes, two rRNA genes, one origin of replication on the light-strand (OL) and a control region (CR). The overall base composition is 28.5, 25.4, 29.4 and 16.7% for A, T, C and G, respectively. The 13 PCGs encode 3797 amino acids in total, most of which use the initiation codon ATG except COI use GTG, and TAA or TAG as the stop codon, except COII, ND4 and Cyt b use an incomplete stop codon T. Additionally, a phylogenetic tree was constructed to explore the taxonomic status of T. obesus, which expects for phylogenetic relationship within Thunnu and further conservation strategies for this species.