Molecular sexing of Japanese cormorants used for traditional fishing on the Nagara River in Gifu City

The Japanese cormorants used in traditional fishing in Japan are wild derived and their sex cannot be determined from their appearance. Applicability of molecular sex determination based on the size difference between CHD1Z and CHD1W introns was confirmed in male and female Japanese cormorants whose sexes had been ascertained by pathological autopsy. All of 21 birds of unknown sex reared by a cormorant fishing master were identified as males. The molecular sexing method will provide valuable information on sex differences of wild Japanese cormorants, including tameness, trainability, behavior and fishing capability, as well as for future trials involving artificial reproduction.