Changes of nutrient composition in the ovaries and hepatopancreas of mud crab Scylla paramamosain broodstock and their offspring performance at different salinities

The mud crab Scylla paramamosain is a major marine crab species for aquaculture in the southern coastal regions of China. This study investigated the differences in the quality of low-salt cultured and wild mud crabs and the the salinity tolerance and growth performance of their offspring. Ovarian development and fatty acid and amino acid compositions in the hepatopancreas and ovaries of mature low-salt and wild mud crabs were compared. The gonadosomatic index was significantly lower, but the hepatopancreatic index was significantly higher in the lowsalt mud crab than in the wild mud crab. The contents of C18:1, C22:6n3 (DHA), DHA/EPA, and n-3/n-6 fatty acids in the ovaries and hepatopancreas of the low-salt mud crab were significantly higher than those of the wild mud crab. Except for proline in the hepatopancreas of the low-salt group, there were no significant differences in amino acids in the ovaries and hepatopancreas between the two groups. Although the survival rate of larval mud crabs in the low-salt mud crab was significantly higher than that in the wild mud crab when the salinity was 24%o, there was no significant difference in the juvenile survival between the two groups. However, the survival rate of larval and juvenile mud crabs in the low-salt group was significantly higher than in the wild group when the salinity was 5 %o and 3 %o, respectively. The final body weight, average weight, weight gain, and specific weight gain rate of male and female offspring in the low-salt group were significantly higher than in the wild group. However, the weight gain and specific growth rate of male offspring in the low-salt group in September-October were significantly lower than those of male mud crabs in the wild group. This study indicates that the mud crab can be domesticated for culture and breeding at low salinity.