池塘养殖中华绒螯蟹扣蟹附肢自切规律的研究

Study of limb autotomy patterns of juvenile Chinese mitten crab(Eriocheir sinensis) reared in earth ponds

对中华绒螯蟹扣蟹培育池塘中幼蟹的自切规律进行了调查研究,结果显示：1）池塘养殖幼蟹的自切率较高,达29.2%,但无性别差异;根据体重将幼蟹分成4种规格（大：6～8 g;中：4～6 g;小：2～4 g;极小：0～2 g）,就不同规格扣蟹而言,中等规格扣蟹的自切率相对较高,但4者之间差异不显著（P〉0.05）。2）大多数个体自切一条（50%～60%）或2条附肢（25%～35%）,自切3个或3个附肢以上的比例较低,自切5条附肢比例仅为2%。3）附肢自切通常发生在幼蟹身体的其中一侧,身体两侧同时自切的概率较低（12%～15%）。4）各肢型受到自切的概率不同,后3对附肢的自切率显著高于第1第2对附肢（P〈0.05）,自切螯足的概率最低。5）整体上,扣蟹雌雄个体的自切规律基本一致,不存在显著的性别差异（P〉0.05）。

Limb autotomy is a common phenomena for crustacean. This study was conducted to investigate the patterns of limb autonomy for juvenile Chinese mitten crab Eriocheir sinensis reared in earth ponds,and the results showed that whether males or females,high percentage of limb autonomy was found on juveniles,accounting for 29. 2% of total crabs; when all juvenile crabs were divided into three grades based on body weight,i. e. large： 6 ～ 8 g; middle： 4 ～ 6 g; small： 0 ～ 4 g,the highest ratio of limb autotomy was occurred in medium sizes among four size groups. However,no significant difference was observed（ P〉0. 05）; most individuals lost one（ 50 ～60% total crabs） or two legs（ 20 ～ 35% total crabs）,while the percentage was low for the crabs lost three or more than three legs and it was quite rare（ 2%） for the crabs lost five limbs. Autotomy often happened at one side of the crab,and lower incidences of symmetrical injury was observed in our study; Furthermore,the incidences of limb autotomy is quite different for each limb,the lost chance of last three pairs of legs was significant higher than that of first and second pairs of legs（ P〈0. 05）,while the ratio of chelipeds loss was the lowest among all limbs.