Species and lineage identification for yellowfin Thunnus albacares and bigeye T. obesus tunas using two independent multiplex PCR assays

Based on nucleotide substitutions in four mitochondrial DNA regions, we developed multiplex PCR assays for identifying species/lineages in yellowfin Thunnus albacares and bigeye T. obesus tunas. The validity of the assays was tested on 3247 individuals of seven Thunnus tuna species ( T. orientalis , T. thynnus , T. maccoyii , T. alalunga , T. albacares , T. obesus , and T. tonggol ). Bigeye and yellowfin tunas were almost completely discriminated. Of the two intraspecific mitochondrial lineages—alpha (clade II) and beta (clade I)—of bigeye tuna, the former is known to predominate in the Atlantic but to be almost nonexistent in the Indo-Pacific. The multiplex PCR methods we developed were able to discriminate these two lineages. These multiplex PCR assays were more rapid and robust than conventional methods for identifying these tunas and their intraspecific lineages.