分布于雅砻江中游厚唇裸重唇鱼的饵料生物组成与摄食特性

Food organism compositions and feeding characteristics of Gymnodiptychus pachycheilus in the middle reach of Yalong River

摘要:

目的 研究雅砻江中游现有厚唇裸重唇鱼的饵料生物组成与摄食特性。方法 通过分析于2020年10月至12月、2021年3月和2022年5月在四川省甘孜藏族自治州内新龙县至雅江县江段采集的207尾厚唇裸重唇鱼样本的摄食强度，并分别选取30与53尾样本测量肠道长度、分析肠道内容物。结果 雅砻江中游厚唇裸重唇鱼的总体摄食强度较低，且在繁殖期的摄食强度最低。厚唇裸重唇鱼所摄食饵料生物的总种类数为38种，主要饵料生物为大型无脊椎动物中的纹石蛾幼虫，并兼食等片、舟形藻、桥弯藻、异极藻等着生藻类。厚唇裸重唇鱼肠道系数(IC)平均值 为1.61±0.06，处于已有研究裂腹鱼类的中下游水平；其饵料生物Shannon-Wiener多样性指数(H′)和Pielou均匀度指数(J)分别为2.10和0.58，处于已有研究裂腹鱼类的上游水平。此外，Amundsen图示法和Schoener重叠指数结果均表明，雅砻江中游厚唇裸重唇鱼不同体长组及不同性别之间的饵料生物重叠程度较高，而不同季节采集样本之间的饵料生物重叠程度较低。结论 雅砻江中游厚唇裸重唇鱼属广食性鱼类，也属偏食底栖无脊椎动物的杂食性鱼类，且相较于体型与性别而言，季节更替对其饵料生物组成的影响更为明显。研究结果丰富了厚唇裸重唇鱼的基础生物学资料，同时为其野生资源保护、人工驯养、饲料研发等提供了基础数据。

Abstract:

Gymnodiptychus pachycheilus, a native fish species of the Schizothoracinae subfamily in China, is primarily distributed in the upper reaches of the Yellow River and the middle to upper reaches of the Yalong River. To analyze the feeding characteristics (including feeding intensity and its seasonal variation, composition and diversity of food organisms, and feeding strategy) of G. pachycheilus in the middle reaches of the Yalong River, a total of 207 samples were collected from this ragion in Ganzi Tibetan Autonomous Prefecture, Sichuan Province, between October 2020 and May 2022. Specifically, 207, 30, and 53 G. pachycheilus samples were used to assess feeding intensity and food composition among different size, gender, and seasonal groups, measure intestinal length (IC), and analyze intestinal contents, respectively. Results indicated that the overall feeding intensity of G. pachycheilus was low in the middle reaches of the Yalong River, with the lowest intensity observed during the reproduction season. A total of 38 prey species were identified for G. pachycheilus, with Hydropsychidae larvae (a benthic macroinvertebrates) being the primary food source. G. pachycheilus also consumed attached algae of Bacillariophyta (e.g., Diatoma spp., Navicula spp., Cymbella spp., Comphonema spp., etc.). The average intestinal (IC) of 30 G. pachycheilus samples was 1.61±0.06, which was considered a lower-middle level of Schizothoracinae fishes according to the previous studies. The Shannon-Wiener diversity index (H') and Pielou evenness index (J) of the food organisms for G. pachycheilus were 2.10 and 0.58, respectively, indicating relative high levels of dietary diversity and evenness compared to other Schizothoracinae species. Furthermore, analysis using the Amundsen graphic method and Schoener overlap index revealed higher dietary overlap among G. pachycheilus samples from different body length and gender groups, while lower overlap was observed among seasonal groups. Overall, G. pachycheilus in the middle reaches of the Yalong River is an euryphagous and omnivorous species that prefers benthic invertebrates. Seasonal changes had a more significant impact on food composition than body size or sex. The findings of this study enrich the basic biological data for G. pachycheilus and provide a scientific basis for the conservation of wild resources, artificial domestication, and the development of suitable feeds.