入秋后,随着水温的逐渐下降,亲蟹的性腺发育日趋成熟。在北方一些地区,有“七上八下”的说法,讲的就是随着水温的下降,成蟹开始了生殖洄游活动。在河北、天津地区进行河蟹人工育苗生产,亲蟹的交尾抱卵时机多掌握在十月中旬,此时交尾抱卵池的自然水温在15℃左右,亲蟹放入池后,大约经过一周的时间,绝大多数亲蟹达到抱卵。近年来,部分育苗厂家以长江水系河蟹作为亲本,常常出现“黄卵”“掉卵”等不正常现象。经分析与亲蟹的选择和交尾抱卵时机未把握好有直接关系。长江中下游地区由于降温 After autumn, with the gradual decline in water temperature, crab gonadal maturity. In some areas in the north, there is a saying of “seven or eight”, referring to the fact that crabs started their reproductive migrations as the water temperature dropped. In Hebei, Tianjin crab artificial seedling production, crab mating crab mating timing is more mastered in mid-October, when the natural spawning pool of natural water temperature at about 15 ℃, crab into the pool, after about a week’s time, The vast majority of crabs reached the eggs. In recent years, part of the nursery manufacturers to the Yangtze River crab as a parent, often appear “yellow egg ” “eggs” and other abnormal phenomena. Analysis and selection of crabs and crab mating timing is not sure there is a direct relationship. Middle and lower reaches of the Yangtze River due to cooling