Abstract
The karyotypes of the black rats (R. rattus) collected from the harbor area and the vessels from each nationality of Korea, Taiwan, Indonesia and Japan anchoring in the Shimizu port, are analyzed by conventional, G- and C-band stainings. All 68 specimens obtained from the harbor area and the anchoring vessels are the Asian type. Among them 67 have the 2n=42 (Asian type), but the remaining one from the harbor area has 41 chromosomes by the XO type. Based on the number of C-bands of the autosomes, the black rats collected in the Korean and Taiwanese vessels seem to be those migrated from each country.
