Effects of Temperature on Reproductive Performance, Embryonic Quality, and Embryonic Development of Chinese Mitten Crab

To explore the effects of temperature on the reproductive performance and embryonic development of female Eriocheir sinensis broodstock, the reproduction experiments of broodstock crabs under different temperatures (6, 9, 12, 15, 18, and 21°C) were carried out. Each temperature was replicated in three parallel tanks, with 5 male and 10 female crabs stocked in each tank for feeding. The results showed that with the rising of temperature, the mating rate of broodstock crabs increased gradually, the spawning rate, spawning amount, fecundity and reproductive index increased first and then decreased. At 15°C, the spawning rate, spawning amount, fecundity and reproductive index of the broodstock reached the highest and significantly higher than other temperature groups (p < 0.05). At 18°C, the egg diameter of embryos reached the largest. At 18°C, the contents of crude protein, triglyceride (TG) and total cholesterol (CHL) of embryos in E. sinensis were the highest. With the rising of temperature, the embryonic development rate of E. sinensis accelerated, the embryonic development time of the crabs was shortened and the effective cumulative temperature was gradually decreased. At 6°C, embryos stagnate at the fertilized egg stage, while at 9°C, they develop to the multicell stage but cease division thereafter. In conclusion, the best reproductive performance of the Chinese mitten crab was achieved at 15°C and the quality of embryos produced at 18°C was relatively good. The results of this study not only provided basic data for the breeding biology of E. sinensis but also provided scientific support for the conservation of fishery resources in the Yangtze River Estuary.