长江、黄河、辽河水系中华绒螯蟹野生扣蟹的形态学及生化组成

摘要

The Chinese mitten crab,Eriocheir sinensis, is an important aquaculture species in China that is widely dis-tributed in the east Pacific coast of China, from 24°N northwards to the Korean Peninsula, 42–43°N, from 112° to 114°E. Its high market demand, favorable taste and significant advances in hatchery and grow-out techniques have resulted in this crab being cultured widely in ponds, reservoirs and lakes throughout China since the 1990s. As a consequence, aquaculture yields have steadily increased over the past decades, from 8000 t in 1991 to approximately 729900 t in 2013. The main culture areas are located in the three principal drainage basins, i.e. the Liaohe, Yellow and Yangtze Rivers. The Yangtze delta is the largest culture area among the three drainage basins. Although pond-reared populations of E. sinensisoriginated from their native habitats, i.e. the Liaohe, Yellow and Yangtze Rivers, the Yangtze population generally had the largest body size of adult crabs, the best growth performance and the best taste among three populations. Therefore, pond-reared populations ofE. sinensis, originating from the wild Yangtze population, have become the common and major culture population in Middle and East China. Inbreeding depression and adverse selec-tion for smaller-sized crabs eventually resulted in the genetic degeneration of pond-rearedE. sinensis. Moreover, the blind introduction and culture of different populations ofE. sinensisin their native habitat has led to hybrid germplasms for pond-reared populations. Previous studies have shown that wild crab seeds of juvenileE. sinensisshowed different culture performance in ponds, and the wild crab seeds from the Yangtze River system generally had the best perform-ance and attracted the highest price among these wild populations. However, to date, there is no reliable discrimination method to identify the origins of wild crab seeds from different rivers. Therefore, the current study was designed to in-vestigate the differences and similarities of wild juvenile crabs from the three river systems. Based on morphological measures and biochemical analyses, we determined and compared the morphological parameters, hepatosomatic index (HSI), proximate composition, lipid composition and fatty acid composition of wild juvenile crabs from the three river systems. The results showed that: (1) significant differences in morphological characteristics were observed for wild juvenile crabs from the three river systems, including 12 and 18 morphological indices for female and male crabs, re-spectively. However, their coefficient of variation did not reach the threshold value for the subspecies. Cluster analysis showed that the wild juveniles from the Yangtze and Yellow Rivers were pooled and separated into one group, while the wild crabs from Liaohe River were divided into another group. (2) Based on the 7–10 indices with high contribution to the discrimination of wild juveniles from the three populations, different discrimination equations were established for female and male crabs of each population, respectively. The overall accuracy of discrimination was 87.5%. (3) The wild juvenile female crabs from Yangtze River had the highest HIS, while the lowest was found in the males from Liaohe River; female crabs from the Liaohe population contained higher moisture and protein levels in their hepatopancreas, while females of the Yangtze population had the lowest moisture, crude protein and carbohydrate contents. The wild crabs from Liaohe River had the highest moisture content in their body muscle, while the crabs from Yangtze River con-tained the highest body crude protein and total lipid contents, but the lowest carbohydrate levels. (4) For the lipid composi-tion, except for the hepatopancreas of male crabs, the triglyceride levels in the tissues of Yangtze crabs were signifi-cantly higher than those of the other two populations, while the tissue of the Yellow River crabs had lower free fatty acid and cholesterol contents, but the highest levels of phospholipids. (5) The Yellow River crabs had the lowest levels of 18 : 1n9 and 18 : 2n6 in the hepatopancreas and body muscle, but the highest contents of 20 : 5n3 and 22 : 6n3. Overall, the hepatopancreatic differences in fatty acid composition among crabs of the three river systems were higher than those in the body muscle. In conclusion, there were significant differences in morphological indices and biochemical composition in the wild juvenileE. sinensis from the three river systems, which might be related to their growth environment, natural diets and heredities. These results not only provide useful information for the dis-crimination of wild seeds from the Liaohe, Yellow and Yangtze Rivers, but also contribute to the evaluation of wild germplasm resources and the rational utilization of natural resources of wildE. sinensis.%探讨长江、黄河和辽河水系中华绒螯蟹(Eriocheir sinensis,以下称河蟹)野生扣蟹的异同,对于河蟹种质资源评价和养殖生产具有重要的现实意义。本研究采用形态学测量和生化分析方法,测定和比较了长江、黄河和辽河三水系野生扣蟹(以下简称长江蟹、黄河蟹和辽河蟹)的形态学、肝胰腺指数(HSI)、常规生化成分、脂类和脂肪酸组成差异。结果表明,(1)三水系野生扣蟹的形态学特征差异较大,三水系雌雄扣蟹分别有12和18个形态学指标差异显著,但其差异系数均未达到亚种间的差异阈值,聚类分析将三水系野生扣蟹分为两组,长江和黄河水系为一组,辽河水系为另一组。(2)筛选判别贡献率较大的7～10个指标,对三水系雌雄扣蟹分别建立判别方程,综合判别准确率达87.5%。(3)长江雌蟹HSI最高,辽河雄蟹HSI最低；辽河雌蟹肝胰腺的水分和蛋白含量较高,长江雌蟹水分、粗蛋白和总糖含量最低；辽河蟹躯体肌肉水分含量最高,而长江蟹躯体蛋白和脂肪含量最高,但总糖含量最低。(4)就脂类组成而言,除了雄体肝胰腺外,长江蟹组织中的甘油三酯含量均显著高于其他两个水系,黄河蟹游离脂肪酸和胆固醇百分含量相对较低,但磷脂含量最高。(5)黄河蟹肝胰腺和躯体肌肉中18：1n9和18：2n6含量最低,但其20：5n3和22：6n3含量最高,三水系肝胰腺中的脂肪酸差异大于肌肉间的差异。因此,三水系河蟹野生扣蟹的形态学和生化组成均存在较大差异,可以据此进行综合鉴别。