雅砻江下游鱼类资源调查及保护措施

分别于2007年4-5月和2008年4-5月对雅砻江下游鱼类资源现状进行了调查,共设置采样点9个,采集鱼类54种,另收集鱼类21种,共隶属于7目19科。调查结果表明,雅砻江下游水域生态环境的变化导致鱼类物种组成、种群结构发生了变化,珍稀鱼类数量急剧减少。与历史资料相比,鱼类种类数量从98种下降到75种。另外,渔获物分析结果表明,雅砻江下游鱼类资源呈现低龄化、小型化的趋势。雅砻江下游珍稀保护鱼类长薄鳅、细鳞裂腹鱼、鲈鲤和四川华吸鳅在调查区域内的分布范围有显著差异。     

雅鲁藏布江尖裸鲤胚胎和仔稚鱼发育研究

尖裸鲤（Oxygymnocypris stewartii）成熟卵呈圆形,黄色,沉性,卵径（2.57±0.07）mm,受精卵吸水充分膨胀后卵径为（3.22±0.07）mm。水温9.5～11.8℃,尖裸鲤胚胎发育历时265h,根据胚胎发育的外部形态及典型特征,将其分为受精卵、胚盘形成、卵裂、囊胚、原肠、神经胚、器官分化和孵...     

四川裂腹鱼摄食习性与资源保护

对采自乌江上游的190尾四川裂腹鱼（Schizothorax kozlovi）进行了食性分析。结果表明,天然水域中四川裂腹鱼以水生昆虫、藻类、水生植物、环节动物、软体动物和原生动物等为食,其营养级为1.72级,属于底栖杂食性鱼类。主要饵料为水生昆虫,出现频率和重量比分别为76.30%和53.22%;其次为藻类,出现频率...     

云南境内南盘江水系鱼类种质资源现状及保护对策

为了解南盘江鱼类资源现状,保护和恢复南盘江鱼类多样性,2008年6月至2010年3月,对云南省境内南盘江鱼类现状进行实地考察,结合中国科学院昆明动物研究所馆藏标本和历年相关记录,分析南盘江鱼类种质资源现状。结果表明,云南境内南盘江及其附属湖泊共有鱼类8目、20科、71属、160种;其中,土著种137种,特有种93种,外来种23种。鲤科鱼类最多,有94种,占鱼类总数的58.8%,其次为条鳅科32种,占总数的20.0%,爬鳅科7种,占总数的4.4%。南盘江鱼类种类众多,但由于人为影响,河流污染比较严重,目前已有24种鱼类被列为濒危种类。分析南盘江近两年的鱼类种质资源现状,发现土著种类的数量大幅下降,这与南盘江河流环境恶化和水电开发力度增大密切相关。     

赣江中游水利枢纽群生态优化调度的预测分析

针对水利枢纽工程对河流生态系统的影响,基于鱼类产卵期较大时间尺度(月为周期)的河道生态蓄水过程和小时间尺度的场次模拟生态洪水过程2种工况,建立赣江中游万安、石虎塘和峡江梯级枢纽群联合生态优化调度模型,分析生态调度对水库群经济效益的影响.数学模型中生态流量过程为约束条件之一,以水库群发电量最大作为调度目标,求各水电站的流量过程和发电量,采用逐次优化算法(POA).结果表明,考虑生态调度后,系统总体发电量减少约185万kW·h,减少1.65％,对水库经济效益即总发电量的影响不大,实施水利枢纽群生态优化调度有利于减缓工程对河流生态系统的影响.     

Pansteatitis in polluted Olifants River impoundments: nutritional perspectives on fish in a eutrophic lake,Lake Loskop,South Africa

This study compares the aetiology of pansteatitis in Lake Loskop, relative to two other impoundments along the Olifants River. Macroscopic and microscopic pathology, age determination and analysis of stomach content, fatty acids and stable isotopes explain the high prevalence of pansteatitis in Oreochromis mossambicus (Peters) and several other species in Lake Loskop. All the dietary indicator comparisons between pansteatitis‐affected and healthy fish fail to support a systemic cause. Pansteatitis in Lake Loskop was linked to size and weight of O. mossambicus, but not to ontogenic age. Fish in Lake Loskop showed abnormally high omega‐3 to omega‐6 fatty acid ratios normally only found in marine fish with no significant difference in degree of assimilation of these fatty acids between pansteatitis‐affected and healthy fish. This explains the vulnerability to, but not the occurrence of, pansteatitis. As a cause for the pansteatitis, these results point towards sporadic vitamin E‐depleting trigger events, known sporadic fish die‐off occurrences that provide surviving fish with a rich source of rancid fats on which to scavenge. The mechanism ties pansteatitis to eutrophication and trophic cascade effects, the intrinsic drivers of the disease and suggests an adaptive management strategy that might be applied by relevant conservation authorities.     

Implications of piscine predator control on the federally listed fountain darter

One strategy for protecting the federally listed fountain darter, Etheostoma fonticola (Jordan & Gilbert), during low flow conditions is the removal of piscine carnivores [in this case, largemouth bass, Micropterus salmoides (Lacepède)]. However, headwater spring communities of the Comal and San Marcos rivers include another potential predator [red swamp crayfish, Procambarus clarkii (Girard)]. Removal of piscine carnivores could produce cascading effects by increasing crayfish consumption of benthic fish. The purpose of this study was to evaluate if piscine carnivore removal will lessen predatory pressure or induce a trophic cascade with crayfish increasing and causing declines in fountain darter. The numbers of fountain darter consumed were quantified among three predator treatments (red swamp crayfish only, largemouth bass only and red swamp crayfish and largemouth bass combined) and vegetation treatments (vegetated and non‐vegetated) at three temperature regimes (18, 22, 27°C). Vegetation had no effect on fountain darter predation. Among temperature trials, largemouth bass only and red swamp crayfish and largemouth bass combined consumed similar numbers of fountain darter, and red swamp crayfish only consumed the least numbers of fountain darter, except at 22°C. Largemouth bass did not consume more red swamp crayfish than fountain darter. Therefore, largemouth bass removal appears to be a viable option for reducing fountain darter predation during periods of low flow.     

Otolith chemistry indicates walleye movement and entrainment in a large serial reservoir system

Understanding fish movement in impounded river systems is important for fisheries management. Otolith chemistry was used to examine walleye Sander vitreus (Mitchill) intra‐ and inter‐reservoir movement in four Missouri River impoundments. Age‐0 individuals were reclassified with 75%–93% accuracy to known natal sites, allowing for reliable evaluation of movement patterns of age‐1 and older fish. Nearly half of walleye occupied the same location annually (i.e. site residency) between 2009 and 2010. In 2011, during the largest flood on record since 1898, downstream movement (49% of age‐1 and older fish) exceeded upstream movement (7%) and site residency (33%) across the study area. After the flood, most walleye moved downstream within reservoirs (45%) or were site residents (37%). Entrainment occurred most frequently during the flood year and was proportionally greatest in downstream reservoirs. Otolith chemistry is useful for understanding walleye movement and entrainment and is a tool for fisheries management with applications such as informing reservoir water releases, harvest regulations and habitat protection and rehabilitation within and outside the Missouri River reservoir system.     

锦江鱼类资源现状与物种多样性分析

2013年8月—2016年8月对沅江水系支流锦江的鱼类资源现状进行了调查。通过向渔民购买、现场捕捞等方式,共调查野生鱼类43种,隶属于5目11科39属,其中鲤科鱼类25种,占总种类数的58.1%。调查到新记录种5种,分别为大鳞副泥鳅(Paramisgurnus dabryanus)、吻(Rhinogobio typus)、洞庭华鲮(Sinilabeo tungting)、云南盘(Discogobio yunnanensis)和大眼鳜(Siniperca kneri)。干、支流均以底层鱼类为主,种类数分别占各自总数的55.8%和71.4%。对比历史资料,G-F多样性指数呈下降趋势。对干流渔获物种类的周年统计发现,出现频率在50%以上的鱼类有8种,其中泥鳅(Misgurnus anguillicaudatus)、鲤(Cyprinus carpio)、鲫(Carassius auratus)和鲇(Silurus asotus)的出现频率均达到97.3%。     

基于PSR模型的黄河陕西段鱼类增殖放流生态安全评价

基于压力、状态、响应模型(PSR)和层次分析法(AHP),确定17项指标通过数据的标准化处理,指标权重赋值、权重一致性检验、评价等级确定以及评价模型的构建,用生态安全评价黄河陕西段鱼类增殖放流效果,分析生态安全所面临的主要问题。结果表明:黄河陕西段2013年增殖放流生态安全度(ESI)评价等级为Ⅱ级,为良好状态;2014年评价等级为Ⅲ级,处于一般状态;2015年评价等级为Ⅳ级,处于较差状态,属于临界不安全状态以下水平。生态安全形势呈现出逐年下降局势。不安全状态受到影响较大的前3个指标是:黄河径流量变化影响、重要生境保持率和公众资源环境保护意识的影响,3个指标下降值占到下降ESI值的64.93%。其次还受到污水排放达标率、鱼类增殖放流量、政策和管理水平、鱼类生物多样性指数、保护区建设、水质综合污染指数、群落结构等诸多因素影响。研究显示,现阶段增殖放流对黄河生态安全有一定影响,还存在一定提升空间。