Abstract: It is significant of rapid measurement of crab sperm counts to study sperm cryopreservation and population reproduction.A spectrophotomeric method was used to determine the sperm concentration of swimming crab Portuns trituberculatus and Chinese mitten crab Eriocheir sinensis at wavelengths of 380,520,and 760 nm.It was found that the sensitive and reliable rapid measurement of crab sperm counts was carried out at 520 nm.A linear relationship between sperm concentration（C） and photometric absorbance（A） was observed for sperm concentration of swimming crab and Chinese mitten crab.The best regression equation for the standard curve at 520 nm was expressed as A= 0.058×C（R2=0.9928） for the swimming crab and A=0.061×C（R2=0.9892） for Chinese mitten crab.Statistical analysis showed that this spectrophotomeric method was fast and accurate for sperm count.

Key words: Portuns trituberculatus, Eriocheir sinensis, spectrophotomeric method, sperm concentration