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Although pond culture is the major culture method for Chinese mitten crab (Eriocheir sinensis) in China, the pattern of ovarian development in pond-reared E. sinensis remains unclear. This study investigated the changes in ovarian morphology and histology, gonadosomatic index (GSI), hepatosomatic index (HSI), and monthly variation of the ovarian development pattern during the ovarian maturation of pond-reared female E. sinensis. Based on the pubertal moult, and ovarian morphology and histology, the ovarian development cycle of E. sinensis could be divided into five stages, i.e., Stage I: the ovary appears thin ribbon-like and translucent, dominated by oogonia (OG) and previtellogenic oocytes (PRO); Stage II: the ovary appears milk white or buff, dominated by endogenous vitellogenic oocytes (EN); Stage III: the ovary appears orange or light brown, dominated by exogenous vitellogenic oocytes (EX); Stage IV: the ovary appears crimson red or brown and ovarian lobes occupy most available body cavities. The major oocytes were nearly mature oocytes (NO); Stage V: the ovary appears deep purple and is filled with mature oocytes (MO). During ovarian maturation, the GSI increased significantly and a significant, positive correlation was found between the GSI and the mean long diameter of the oocyte from stage III to stage V. However, a significantly negative correlation was found between GSI and HSI. The ovarian development of pond-reared female E. sinensis was not synchronous, most of the pubertal moults were found until mid-late August. At the end of August, the percentages of females that reached ovarian stages II and III were 55 and 24%, respectively. After that, the ovarian development of pond-reared female E. sinensis became fast, and females with stage III or more advanced ovaries were found to be in excess of 80% by the end of September and onward. From the end of November to late December, the GSI of female E. sinensis did not increase significantly, which indicated pond-reared females had reached mature or nearly-mature ovaries by the end of November. [ABSTRACT FROM AUTHOR]

The swimming crab, Portunus trituberculatus (Miers, 1876) is one of the most common edible marine crabs in East Asia. In this study, a multiple mixed probes hybridization method was used to isolate microsatellites to improve experimental efficiency and streamline the procedure. The mix of biotinylated probes included microsatellite GA, CA and CAT motifs. Fourteen novel polymorphic microsatellite loci were isolated and characterized from a wild population of P. trituberculatus. The number of alleles varied between three and nine, and the observed and expected heterozygosity at population level ranged from 0.542 to 1.000 and 0.616 to 0.851, respectively. Two loci, Ptr1 and Ptr3, significantly deviated from the Hardy-Weinberg equilibrium (P<0.01). These informative microsatellite markers could be useful for future population genetic analyses and genome mapping studies in this species. [ABSTRACT FROM AUTHOR]

The juvenile Chinese mitten crabs Eriocheir sinensis (1.40 ± 0.43 g) were cultured in water of 5.34 ± 0.43 (hypoxia, treatment group) and 21.02 ± 0.06 kPa (high dissolved oxygen (DO), control group) DO for 24 h, respectively. The total hemocyte counts (THC), the hyaline hemocyte counts were measured at 0 and 24 h in the treatment group, and superoxide dismutase (SOD) activity, concentrations of lactic acid and hemocyanin (Hc) in hemolymph and the metabolism of hepatopancreas (concentrations of glucose, total cholesterol, uric acid, total protein, urea, triglyceride in hepatopancreas) were assayed at 0, 2, 8, and 24 h in both treatment and control groups. The hyaline hemocyte counts and THC decreased significantly by 66 and 49% after exposure to hypoxic water for 24 h, respectively. SOD activity, Hc and lactic acid content were significantly affected in treatment group, and there were significant differences between treatment and control groups. In the treatment group, the concentration of glucose, cholesterol and uric acid in hepatopancreas had a significant variation for 24 h. The concentration of total protein, urea and triglyceride between treatment and control groups was not significantly different after 0, 2, 8, 24 h. However, there were significant differences between treatment and control groups in terms of total protein, glucose, and uric acid concentration. Taken together, the effect of hypoxia is comprehensive in juvenile Chinese mitten crab Eriocheir sinensis. [ABSTRACT FROM AUTHOR]

Precocious puberty is one of the major constraints to the further development of Chinese mitten crab ( Eriocheir sinensis) farming industry. Although dietary phospholipids (PL) and highly unsaturated fatty acids (HUFA) supplementation have been shown to enhance the growth of larval E. sinensis in other studies, it is still unknown whether this also leads to a higher precocity rate for juvenile E. sinensis. This study was conducted to investigate the effects of dietary PL and HUFA on precocity, survival, growth and hepatic lipid composition of juvenile E. sinensis. Two diets were formulated with PL [3.95% dry weight (DW)] and HUFA (0.98% DW) supplementation (diet A) and without PL and HUFA supplementation (diet B) and fed to juvenile E. sinensis. Although dietary PL and HUFA levels did not significantly affect the survival and growth performance of juvenile E. sinensis, compared with crabs fed diet A, a higher precocity rate was found among juvenile E. sinensis fed diet B ( P=0.051). A higher total lipid content, but significantly lower levels of HUFA and PL ( P<0.05) were found in the hepatopancreas of crabs fed diet B than in those fed diet A. Meanwhile, the precocious females had significantly lower hepatosomatic index, arachidonic acid (20:4n-6), eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) contents in their hepatopancreas when compared with that of the normal immature juveniles ( P<0.05). The results suggest that the occurrence of precocious puberty among farmed juvenile E. sinensis could be reduced by the inclusion of appropriate level of dietary PL and HUFA. [ABSTRACT FROM AUTHOR]

The present study investigated the external and histological changes in the ovary and measured the gonadosomatic index (GSI) and hepatosomatic index (HSI) during the re-maturation of the Chinese mitten crab Eriocheir sinensis. The results show that the ovarian re-maturation cycle of this crab species can be divided into four stages, i.e. Stage I: the ovary had an X shape and appeared milky white or with a mottled buff colour, and the dominant gametocyte at the stage were oogonia (OG, 28.3%) and previtellogenic oocytes (PR, 31.6%); Stage II: the ovary appeared light yellow or tan in colour, dominated by endogenous vitellogeic oocytes (EN, 69.3%). The yolk globules of unreleased mature oocytes (MO) from the previous spawn were absorbed, leaving many vacuoles in the retrogressing MO; Stage III: the ovary appeared crimson red or deep purple, and although the main type of gametocyte was exogenous vitellogenic oocytes (EX), near-mature oocytes (NO) could also be found in the late phase of the ovarian development stage; Stage IV: the ovary was ripe and filled with MO that contained large yolk globules. During the period of the second ovarian maturation cycle, the GSI increased significantly from the time just after the first spawning ( P<0.01). However, although HSI appeared to decrease within days after spawning (DAS), no significant correlation was found between GSI and HSI or between HSI and DAS ( P>0.05). Furthermore, the final GSI and the volume of MO of E. sinensis during the second maturation cycle were drastically lower than those of the first maturation cycle. [ABSTRACT FROM AUTHOR]

After feeding female Eriocheir sinensis on an optimized formulated diet or fresh razor clam Sinonovacula constricta for 7 months, their reproductive performance and offspring quality were compared. To evaluate diet nutrient contents, the proximate, fatty acid and amino acid compositions of the formulated diet and the razor clam were analysed. The nutritional value of the diets was determined by assessing survival, gonadosomatic index (GSI) and hepatosomatic index (HSI) of female crabs from both diet treatments, together with the percentage of females that spawned, total egg production per female and fecundity (number of eggs g−1 female wet weight). Furthermore, the quality of eggs and newly hatched larvae from the two dietary treatments were determined using the following parameters: egg diameter, wet weight and dry weight, hatchability, proximate and fatty acid profile of eggs, larval carapace length, resistant to starvation and osmotic shock, larval survival and development to the zoea II stage. Higher protein, phospholipids (PL) and amino acids (AA) contents were found in the razor clam while the formulated diet contains higher levels of ash, total lipid (TL) and 18:1n-9, 18:2n-6 and 22:6n-3 fatty acids. Although female crabs fed the two different diets showed similar reproductive performances, newly hatched zoea I larvae produced by the crabs fed the formulated diet had significantly longer mean carapace length and shorter development time to the zoea II stage under identical culture condition ( P<0.05). Moreover, dietary fatty acid appeared to have more significant effects on the fatty acid composition of the hepatopancreas than it did on mature ovaries or eggs. This suggests that the fatty acid profile of mature ovaries is indicative of the specific fatty acid required for ovarian development in E. sinensis. In conclusion, our results show that the optimized formulated diet developed in this laboratory can totally replace the razor clam, a broodstock food widely used in E. sinensis hatcheries in China. This encouraging result should facilitate more reliable hatchery production of this important aquaculture species. [ABSTRACT FROM AUTHOR]

The morphological characteristics, tissue indices, proximate and fatty acid compositions of hepatopancreas, gonad and muscle of pond-reared (PR) and lake-stocked (LS) Eriocheir sinensis broodstock were compared. Lake-stocked crabs are characterized by a blue carapace, white abdomen, golden legs and yellow setae while PR crabs have a brown carapace, grey abdomen, black legs and similar yellow setae. The carapace length and width of PR crabs were significantly less than those of LS crabs of the same wet weight (WW). The results showed that the hepatosomatic index (HSI) of PR males was significantly higher, but the gonadosomatic index (GSI) was significantly lower for PR females when compared with LS individuals of the same sex. Regardless of their origin, the muscular index (MI) of males was higher than that of females. The hepatopancreas of LS crabs had higher protein levels and lower lipid levels compared with PR crabs. The results of proximate analysis of male gonads from two different sources were similar, while the protein level in the ovary of LS females was higher than that of PR females. The tissues of males had higher water content but lower lipid and protein levels compared with females regardless of their source. The LS crabs had higher highly unsaturated fatty acid (HUFA) levels than PR crabs in their gonad and hepatopancreas. In conclusion, our results suggest that the nutritional quality of LS crabs is better than that of PR crabs, the nutritional quality of males is poorer than that of females. The reproductive performance and larval quality of crabs from these two rearing systems should be further verified. [ABSTRACT FROM AUTHOR]