川陕哲罗鲑幼鱼生境选择偏好性研究

Sichuan taimen, a typical land-locked salmon fish, is categorized as second-class national protected animal species. The population was endangered in almost of their historical range and the species is on the verge of extinction. Fortunately, 19 adults and plenty of juveniles were captured in the Taibai River of Qinling Mountains in September, 2012. It is not only the rediscovery of the species in the Taibai River during the past 15 years, but also the largest population documented in the nearly past 30 years in the whole country. This finding brings hope and opportunity to the population enhancement and recovery. The knowledge of habitat characteristic is the basement for the protection program of Sichuan taimen, thus, this proposal aims to learn the habitat requirements of Sichuan taimen juvenile from macro to micro scale. Firstly, investigating the basin features (flow, drainage area, slope, vegetation coverage, etc), physical and chemical characters of water (DO, pH, water temperature, etc) and aquatic organisms (zooplankton, phytoplankton, macrobenthos, etc) by literature review and on-site sampling. Then, analyzing the distribution pattern of the juveniles in consideration of different reach types and riparian types by trap fishing and river habitat indicators measuring, drawing the fitness curve of Sichuan taimen juveniles in reach scale. Finally, learning the ecological adaptability and selection of juveniles to the bottom substrate and other microhabitat environment by underwater shooting and microhabitat measurement, constructing and testing microhabitat selection model. The results of this research will be contributable for habitat conservation, habitat amendment, ex-situ conservation and also be helpful in understanding the mechanism of freshwater salmon’s specificity and adaptation in habitat selection.

川陕哲罗鲑为国家二级保护动物，属典型的陆封型鲑科鱼类，目前多个历史分布区内的自然种群濒临灭绝，保护前景岌岌可危。本研究拟在现存自然种群的太白河内开展川陕哲罗鲑幼鱼的生境选择研究。通过文献调研及现场测量掌握太白河的基本环境特征及水生生物现状；然后通过虾笼捕捞和河段生境指标的测量，分析幼鱼的分布密度与河段类型和滨水生境的关系，获得幼鱼的河段适合度曲线；通过水下摄像观察和微生境测量，分析幼鱼对不同河床质及河床微生境的适应性和选择性，构建并验证微生境选择模型。最终获得川陕哲罗鲑幼鱼在河流、河段及微生境尺度上的生境需求及选择偏好。项目的研究结果不仅可以为川陕哲罗鲑栖息地的保护、受损栖息地修复、迁地保护等提供技术支撑，还有助于了解淡水鲑鱼的特异性和可塑性在环境选择中的作用机理。

川陕哲罗鲑为国家二级保护动物，属典型的陆封型鲑科鱼类，目前多个历史分布区内的自然种群濒临灭绝，保护前景岌岌可危。本研究在太白河内开展川陕哲罗鲑幼鱼的生境选择研究。调查和研究内容包括1）太白河的生境特征；2）川陕哲罗鲑的分布及资源量；3）川陕哲罗鲑幼鱼在河流、河段及微生境尺度上的生境需求及选择偏好。本项目的主要结果为：太白河全长59.4km，流域面积377.87km2，多年日平均流量5.2m3/s。平均比降为30.9‰ 。森林覆盖率达到89.5%。流域内常住人口约2.2万人。年平均水温为11.6℃，年平均溶氧为8.76mg/L, 年平均pH为8.59mg/L，年平均电导率为163.14us/cm，平均流速为1.69m/s。太白河中的鱼类资源包括拉氏鱥、汉水高原鳅、川陕哲罗鲑、中华花鳅、秦岭细鳞鲑等种类，其中拉氏鱥、汉水高原鳅2种为优势种。在太白河采集到浮游植物、浮游动物、底栖动物分别为47、13和18种，其平均生物量分别为1.55mg/L 、0.20mg/L 和2.75g/m2。根据样段估算法，估算出太白河川陕哲罗鲑的资源总量为3814尾（3624-4005），其中成鱼的资源量为1286尾（1233-1339）；幼鱼的资源量为2528尾（2438-2619）。河段生境指标的相关性分析结果显示，覆盖度和河段生境多样性指数、高程与弯曲度、高程与覆盖度、弯曲度与湿润率、弯曲度与覆盖度呈现显著的相关性，模拟了川陕哲罗鲑幼鱼对各河段因子的适合度曲线。幼鱼与微生境环境因子的关系分析表明，低规格组的幼鱼偏爱选择流速较低、水深较浅的近岸带栖息。本项目的研究结果不仅可以为川陕哲罗鲑栖息地的保护、受损栖息地修复、迁地保护等提供技术支撑，还有助于了解淡水鲑鱼的特异性和可塑性在环境选择中的作用机理。