我国伊犁河鱼类群落结构及外来鱼类适生性

2012-2019年，在我国伊犁河流域的6个断面开展了鱼类群落结构调查，结果显示我国伊犁河流域现有鱼类共计29种，大多属于鲤形目。鱼类群落组成与20世纪末期相比发生了变化，银色裂腹鱼、短头鲃、银鲫、鲢、北方泥鳅在本研究中未出现，尤其是银色裂腹鱼，截至目前为止的鱼类资源调查中，均无捕获记录。历史研究中未见的乌鳢与大口鲇在本研究中有捕获。外来鱼类的出现率和数量均有所增加。对鱼类群落结构特征进行分析，显示伊犁河流域鱼类群落多样性较低，下游干流和上游支流的鱼类群落结构差异较大。现阶段，我国伊犁河流域主要的优势种外来鱼类有鲤、和鲫。利用最大熵生态位模型（MaxEnt）对鲤、和鲫的适生区域进行预测，与鱼类资源调查获得的鱼类实际分布区对比，显示鲤和在我国伊犁河流域的分布范围与预测结果是吻合的，而鲫在进入伊犁河流域之后开始向上游支流河段扩散。由于这几种外来鱼类在一开始引入的时候未采取管控措施，又具有极强的适应能力，且伊犁河流域的鱼类多样性较小，因此极易形成规模并扩散。外来鱼类的入侵，会对土著鱼类造成巨大的威胁。基于本论文研究结论，应当将已发生生态位漂变的鲫其作为重点关注种类，关注外来鱼类的生活史对策，深入研究外来鱼类的入侵机制和诱因；对上游支流河段的生境进行监测，关注气候和水文变化，尤其是土著鱼类产卵场、索饵场和越冬场的变化，尽可能减小人类活动干扰；对伊犁河流域的鱼类资源进行长期监测，关注鱼类群落结构变化，一旦发现异常及时采取措施；增加对土著鱼类的增殖放流；严格控制进出口贸易和增殖放流时夹带的外来鱼类。维护我国伊犁河流域的生态安全。

Fish community structure and habitat suitability of alien fishes in the Ili River, China

A survey of fish community structure was conducted in six sections of the Ili River, China from 2012 to 2019. The results showed that there were 29 species of fish in the Ili River, most of which are belonging to Cyprinidea. Compared to the record at the end of the last century, the composition of fish species has changed. Schizothorax argentatus Kessler, Barbus brachycephaius Kessler, Carassius auratus gibelio (Bloch), Hypophthalmichthys molitrix (Cuvier et Valenciennes) and Misgurnus bipartitus (Sauvage et Dabry) did not appear in the present survey, especially Schizothorax. argentatus Kessler,there is no capture record in the fish resource investigation by far. Channa argus (Cantor) and Silurus meridionalis Chen, which were not captured in historical studies, were presented in this study. Totally, the occurrence and number of alien fishes have increased. According to the analysis of the fish community structure characteristics, there was low diversity in the Ili River, China. It was significantly different between the main stream and the tributary in fish community structure. At present, the main alien fishes are Cyprinus carpio Linnaeus, Hemiculter leucisculus (Basilewsky) and Carassium auratus (Linnaeus) in the Ili River, China. Using Maximum entropy modelling (MaxEnt) to predict the potential distribution of C. carpio, H. leucisculus and C. auratus in the Ili River, and compared with the fish occurrence, it revealed that the potential distribution was consistent with the actual distribution in C. carpio and H. leucisculus. But C. auratus has spread to the tributary compared with the potential distribution. The alien fish have strong adaptability, furthermore, the absence of controlling and prevention at the beginning of their introduction, made the size of their population and habitat were growing larger in the Ili River, which has low fish diversity. The invasion of the alien fishes will introduce a great threat to endemic fishes. To restrain the spread of alien fish, and maintain the ecological security of the Ili River, China, the life history and invasive mechanism of the alien fish should be paid a great attention, especially for C. auratus that has undergone niche drift. The climate and hydrological of the habitat at the upstream tributaries, especially for native fish spawning, feeding and wintering, should be monitored. The long-term monitoring of fish resources and the changes of fish community structure in the Ili River is needed. The artificial propagation and releasing of native fish should be taken. Meanwhile, it is necessary to exercise strict control over the alien fish entrainment with import and export trade or artificial releasing.