A Method to Identify the Sex of Cultured Eel (Anguilla japonica) using the Pectoral Fin Length: Total Body Length Ratio

Abstract Previous methods for identifying the sex of eels were difficult to apply to yellow eels due to their undeveloped gonads. In this study, we investigated easy method to identify the sex of cultured eel, Anguilla japonica, using the ratio between the vertical and horizontal length of the pectoral fin and total body length. Females had longer total body length (TL):horizontal fin length (Fh) and TL:vertical fin length (Fv) ratios than males. Based on our results, we found that both the TL:Fh and the TL:Fv ratio were suitable for determining the sex of cultured yellow eel. We therefore suggest using the TL:Fh ratio to determine the sex of yellow eels under natural conditions (i.e. without anesthetizing or sacrificing the eels). Specially, eels with TL:Fh ratios below and above 31.6 should be identified as males and females. To our knowledge, this is the method to determine the sex of yellow eel.22Nkc