Abstract:Mitten crab (Eriocheir sensu stricto) is an important aquaculture species in China, with three main species: Chinese mitten crab (Eriocheir sinensis), Japanese mitten crab (Eriocheir japonicus), and Hepu mitten crab (Eriocheir hepuensis). Mitten crab has a catadromous life cycle. Paired mitten crabs mate and spawn in estuaries, and the progeny migrate upriver into freshwater rivers to grow. Mitten crab is widely distributed in major basins along the coast of China. Wild mitten crab populations are distributed from the Suifenhe River in the Heilongjiang Province in the north to the Nanliujiang River in the Guangxi Zhuang Autonomous Region in the south. Suifenhe mitten crab is an indigenous wild mitten crab population distributed in the Suifenhe River basin of Dongning City, Mudanjiang City, Heilongjiang Province. It is a highly salt-tolerant aquatic animal, and the current mitten crab germplasm is severely degraded. Therefore, the development of a new mitten crab germplasm is of great significance for crab industry development and salt-alkali aquaculture in China. In September 2020 and 2021, ground cages were used to capture 299 wild crabs (156 females and 143 males) from the Suifenhe River basin of Heilongjiang to investigate the parameters of sexual maturity, body weight (BW) profile, color, total edible yield, and proximate composition. The sexual maturity of wild Suifenhe mitten crab was determined by puberty molting, and BW was measured using an electronic balance. The hepatosomatic index (HSI, %) and gonadosomatic index (GSI, %) were calculated from their respective weights and the ratio of BW. A high-precision spectrophotometer was used to determine the color of the wet and dry samples. Vacuum freeze-drying was used to determine the moisture content of the edible tissues (hepatopancreas, gonads, and muscles). Protein, lipid, and ash were analyzed by the AOAC and Soxhlet extractor method. In late September, wild crabs in the Suifenhe River basin (Dongning Section) in Heilongjiang Province comprised of two stages: immature and sexually mature. The ratio of immature females was significantly lower than that of sexually mature ones (P<0.05); however, it was the opposite for males. Regardless of sex, the average BW of sexually mature individuals was significantly higher than that of immature individuals (P<0.05). The average BW of mature females was (110.51±2.42) g, and the average BW of mature individuals was (147.79±5.94) g. The average BW of sexually mature female crabs was mainly concentrated in the range of 75.00~149.99 g, and the percentage of mature female individuals (≥100.00 g/ind) was 55.94%. The average BW distribution of sexually mature male crabs was relatively scattered, and the percentage of mature male individuals (≥125.00 g/ind) was 60.00%. On September 29, the HSI and GSI of females were significantly higher than those of males, whereas the rates of muscle yield (MY) and condition factor (CF) were higher in males than those in females (P<0.05). The brightness (L*) and yellowness (b*) values of the female carapace were significantly lower than those of the males (P<0.05). The crude protein content in female gonads and muscles was significantly higher than that in male carapace, whereas the moisture content in male gonads was significantly higher than that in females (P<0.05). The results of this study provide basic data for the development and utilization of Suifenhe mitten crab germplasm resources. Wild adult Suifenhe mitten crab had larger BW and a higher percentage of large-sized individuals than pond-reared E. sinensis in the north of China. The proportion of edible tissues, condition factor, color, and proximate composition of Suifenhe mitten crab were not significantly different from those of E. sinensis from the Liao River and Yangtze River. Meanwhile, the ratio of crude protein to crude lipid in ovaries and muscles was in accordance with the human body’s need for high-protein and low-fat foods. Hence, Suifenhe mitten crab is a new crab germplasm with significant development potential. These results provide basic data for the development and utilization of Suifenhe mitten crab germplasm resources.
