Mitochondrial DNA analyses of narrow-barred Spanish mackerel (Scomberomorus commerson) suggest a single genetic stock in the ROPME sea area (Arabian Gulf, Gulf of Oman, and Arabian Sea)

Abstract

We studied the genetic stock structure of Scomberomorus commerson (locally called kingfish) using restriction fragment length polymorphism (RFLP) and direct sequencing analyses of mtDNA samples from seven locations within the ROPME sea area (Arabian Gulf, Gulf of Oman, and Arabian Sea). A 475-bp segment from the D-loop region was screened in 218 samples using six restriction enzymes, resulting in 22 composite haplotypes. Mean nucleotide diversity for the seven populations was 0.025 (±0.000). An AMOVA comparison among groups of individuals inside and outside the Gulf showed 0.49% variation (p = 0.201), whereas the variation of populations within these groups was 0.05% (p = 0.408). The mean FST value for population pairwise comparisons was 0.010. To further resolve genealogies, sequence analysis was performed on a 330-bp fragment from the same segment for 193 fish. The genetic variance estimated across all populations was similar to the RFLP data, indicating a homogeneous distribution consistent with a single intermingling genetic stock. Based on the genetic marker tested, the null hypothesis that kingfish within the ROPME sea area constitutes a single stock cannot be rejected, but considering that a few migrating fish can reduce heterogeneity to where genetic drift is undetectable, panmixia cannot be confirmed. The results cautiously suggest that adopting a single-stock model and regional shared management are appropriate for sustainable long-term use of this important resource. More rigorous genetic testing using additional neutral markers, and mark-recapture experiments to detect spatial movement patterns, are recommended to further elucidate any stock substructure.