Abstract Nucleotide sequences of four distinct calmodulin genes (designated as CaM-A to -D) of the Pacific bluefin tuna (Thunnus orientalis) were compared.Nucleotide sequence divergence between Course a pied - Accessoires - Nutrition - Capsules the coding regions of four genes ranged from JACKETS URBAN 16.0 to 21.6%, and locus-specific eight primer pairs targeting introns were designed.These primer pairs amplified expected size of fragments in five congeneric tuna species, and utility of these primer pairs was investigated using distant fish species.