有关长江流域鱼类资源保护的几个问题

(1) 酷渔滥捕是造成长江中下游渔业资源严重衰退的主要原因. 长江水系有鱼类400余种,其中终生在淡水中生活的纯淡水鱼类有350种左右,另有中华鲟等海河洄游性鱼类10种,还有花鲈等咸淡水鱼类40余种.长江流域是我国淡水渔业最重要的产区,渔产量占全国淡水总产量的60%.长江盛产草鱼、青鱼、鲢、鳙等数十种经济鱼类,被形象地誉为我国淡水鱼类种质资源库.     

三峡水库外来鱼类资源状况初步研究

2020年4～6月和11～12月,在三峡水库干支流8个典型江段开展外来鱼类的种类组成、相对丰度和空间分布特征的初步研究。结果显示：(1)在三峡库区干支流江段共采集到鱼类108种,隶属于8目21科,其中外来鱼类16种,占鱼类总种数的14.81%;(2)在外来鱼类中优势种有3种,分别为短颌鲚(Coilia brachygnathus)、太湖新银鱼(Neosalanx taihuensis)和尼罗罗非鱼(Oreochromis niloticus),其中短颌鲚在除乌江江段以外的其他7个采样江段中均为优势种,相对优势度分布范围为2.05%～18.71%;太湖新银鱼在支流小江和大宁河江段为优势种,相对优势度分别为2.83%和8.39%;尼罗罗非鱼仅在支流小江江段为优势种,相对优势度为1.56%;(3)外来鱼类在干流渔获物中的相对丰度明显低于其在支流渔获物中的相对丰度,其中外来鱼类在支流小江江段渔获物中的体重百分比最高,为12.30%;在大宁河江段渔获物中的数量百分比最高,为57.55%。鉴于目前三峡库区外来鱼类物种的资源状况,建议采取综合防治措施对三峡库区外来鱼类的种群数量进行管理与控制,从而避...     

长江口中华鲟自然保护区及临近水域鱼类种类组成现状

为了解长江口中华鲟自然保护区及其临近水域鱼类种类组成的现状，2004~2008年利用底拖网、插网、定置网和刺网等多种网具对该水域的鱼类组成状况进行了较为系统的调查。共调查到鱼类105种，隶属于18目43科86属，鱼类种类组成以鲈形目和鲤形目为主；生态类型中海洋鱼类和淡水鱼类各37种，河口定居性鱼类25种，洄游性鱼类6种；鱼类种类组成处于长江下游至东海的过渡类型，鱼类食性以底栖生物、有机碎屑和浮游动物食性为主，凶猛性鱼类较少。与以往调查资料相比，调查水域鱼类物种数有所减少，一些重要的物种更是濒临绝迹。保护区水域鱼类不仅具有较高的物种多样性、河口代表性、稀有性和很高的科研价值，同时其生态系统也较为脆弱，并已受到严重威胁，保护区的保护工作显得尤为重要.     

葛洲坝水利工程对长江中游生态水文特征的影响

为了满足人类社会经济发展要求而修建的水利工程,不可避免地对生态环境造成了巨大影响。从生态水文学角度对长江中游的生态水文特征进行了研究。借鉴国外已有的研究成果,建立了一套指标体系包括长期指标、高流量指标、低流量指标、平均变化指标、涨水落水指标和月流量指标,通过分析指标的变化来评价水利水电工程对生态环境的影响。长江中游是最重要的家鱼自然繁殖区,利用建立的指标体系量化并分析了葛洲坝建坝前后长江中游的生态水文特征变化。分析认为,葛洲坝的修建主要影响涨水落水,对其它生态水文特征影响不大;对于鱼类,涨水过程是刺激鱼类产卵的必要条件,葛洲坝的修建对鱼类产卵造成了一定影响。     

长江口口门区潮下带水域鱼类群落组成的季节变化

根据2006～2007年对长江口口门区潮下带鱼类的监测数据，分析了该水域鱼类群落组成的季节变化特征。结果表明：本次调查采获鱼类42种，隶属21科。生态类群以海洋鱼类种类最多（27种），其次为河口定居种（10种），而淡水鱼类、溯河产卵洄游鱼类和降海产卵洄游鱼类种类数很低。S1站点和S2站点类似，均以棘头梅童鱼（Collichthys lucidus）、刀鲚（Coilia ectenes）、龙头鱼（Harpodon nehereus）为优势种。两站点鱼类群落在空间上无显著差异，而时间上均有明显的季节变化，冬季和初春的样品聚为一组（Ⅰ组），夏、秋季的样品聚为一组（Ⅱ组）。通过SIMPER分析可知，两组间的平均相异性较高，达7303，共有17种鱼类对组间的贡献超过90%，如日本鳗鲡（Anguilla japonica）、棘头梅童鱼、矛尾虾虎鱼（Chaeturichthys stigmatias）、刀鲚、焦氏舌鳎（Cynoglossus joyneri）、龙头鱼等。     

大坝截流前后金沙江观音岩水电站鱼类群落功能多样性的变化

人类活动通过对非生物因素和生物多样性的作用从而对生态系统功能产生了巨大的影响。大量的理论和实验研究表明,物种功能性状在连接群落组成改变和生态系统进程转变中起着重要作用。由于物种功能性状的差异,栖息环境改变后,群落中容易适应新环境的物种占据优势,难以适应的物种数量减少甚至消失,从而导致整个群落结构发生改变,进而使整个生态系统进程发生转变。通过评价金沙江观音岩水电站大坝截流前后鱼类群落组成情况,结合不同种类功能性状的差异,采用生物多样性评估方法和功能多样性指数分析方法两种不同手段,对比分析截流前后大坝下游鱼类群落结构和功能多样性的变化,从而分析大坝建设的生态效应。结果表明:Bray-Curtis相异指数前后差异较大,辛普森指数无明显变化;功能多样性指数的变化表明大坝截流对水体中体型较大,口下位,食谱宽度较窄的鱼类生存和活动造成了一定的破坏,导致拥有这些特征的鱼类数量减少甚至消失,降低了下游鱼类群落的功能多样性,进而对该区域整个生态系统功能产生影响。     

南水北调东线工程对长江口渔业资源的影响

工程在５－１０月份调水，对长江口鱼，虾，蟹类影响极小。在１１－４月份调水，对长江口鱼，虾，蟹类略有影响，海水鱼类的数量将有所增加，淡水鱼类和半咸水鱼类的分布范围将向口内扩展，刀鲚，前颌间奶鱼和凤鲚向长江口作生殖洄游的时间将有所推迟，安氏长臂虾，脊尾长臂虾的分布和中华绒螯蟹的产卵场将向口内偏移。     

长江中游洪湖至宜昌江段鱼类空间分布特征的水声学研究

为了解长江中游洪湖至宜昌江段鱼类时空分布变化,于2014~2015年的秋季、春季和夏季,使用Simrad EY60鱼探仪对该江段的鱼类时空分布特征进行了3次水声学调查。结果表明:鱼探仪探测获得的鱼类回波信号与湖底反射信号的图像均比较清晰,且图像的背景噪声较小,长江干流的鱼类多以个体形式进行活动,探测时未发现鱼群。夏季鱼类目标强度(TS值)最高(–47.2±8.6)d B,春季鱼类TS值最低(–60.0±6.4)d B,非参数检验结果显示,3个季节的鱼类TS值差异极其显著(P0.01);3个季节该江段鱼类资源水平分布不均匀,鱼类最大密度分别为63.7 ind./1 000 m3(秋季)、141.4 ind./1 000 m3(春季)和266 ind./1 000 m3(夏季),且3个季节鱼类水平分布差异极显著(F=151.08,P0.01);垂直水层方向上,3个季节的鱼类密度均表现出相同的分布特征,即表层中层底层,各水层3个季节之间的鱼类密度存在极显著性差异(df=2,P0.01);在方差齐性下,采用LSD方法对3个季节各水层之间鱼类密度进行多重比较,结果显示秋季仅表层与底层之间鱼类密度均存在显著性差异(P0.05);春季表层与中层、中层与底层之间鱼类密度均存在显著性差异(P0.05);夏季表层、中层和底层两两之间鱼类密度均存在显著性差异(P0.05)。该江段鱼类时空分布差异与鱼类的越冬、索饵、产卵等因素有关。     

瓯江鱼类资源调查及保护对策

瓯江是浙江省第二大江，鱼类资源丰富，然而至1972年调查以来，尚未有全面的鱼类资源调查研究。对瓯江干流从上游查田镇至下游海口镇的5个采样点进行了较全面的鱼类调查，共采集鱼类标本1 246尾，隶属于5目14科46属60种。相比1972年调查结果，有34种未采集到，其中包括列入中国濒危动物数据库的4种：中华鲟、鲥、香鱼、花鳗鲡；本次调查结果较1972年调查新增19种，其中外来鱼类2种：莫桑比克罗非鱼、大口黑鲈。在对5个采样点的鱼类组成、群落相似度、优势种组成、生物多样性指数等进行分析后，发现瓯江上游鱼类种类以流水性鱼类为主，且生物多样性较高；中下游鱼类种类组成以静水性鱼类为主，且生物多样性较低。本次调查的每日单船渔获量为45 kg/（船·d），仅为1972年的25%，鱼类资源衰退严重。最后，对鱼类资源下降的原因进行了分析，并提出了保护对策     

长江水系四大家鱼种质资源的保护和合理利用

四大家鱼是我国淡水养殖和捕捞的主要对象，本文从影响长江水第四大家鱼种质资源的主要因素出发，对目前鱼类养殖场普遍存在的四大家鱼种质退化的原因进行了分析，提出了保护长江水系四大家鱼天然产卵场，利用长江故道保护和合理利用长江四大家鱼种质资源，保护四大家鱼人工养殖群体的遗传性能，建立长江水系四大家鱼种质资源监测体系等对策。     

Long-term investigations of radiocaesium activity concentrations in carp in North Croatia after the Chernobyl accident

Long-term investigations of radiocaesium activity concentrations in carp in the Republic of Croatia are presented. The radiocaesium levels in carp decreased exponentially and the effective ecological half-life of (137)Cs was estimated to be about 1 year during 1987-2002 and 5 years during 1993-2005. The observed (134)Cs:(137)Cs activity ratio in carp was found to be similar to the ratio observed in other environmental samples. The concentration factor for carp (wet weight) was estimated to be 128+/-74 Lkg(-1), which is in reasonable agreement with model prediction based on K(+) concentrations in water. Estimated annual effective dose received by adult members of the Croatian population due to consumption of carp contaminated with (134)Cs and (137)Cs are small: per capita dose from this source during 1987-2005 was estimated to be 0.5+/-0.2 microSv. Due to minor freshwater fish consumption in Croatia and low radiocaesium activity concentrations in carp, it can be concluded that carp consumption was not a critical pathway for the transfer of radiocaesium from fallout to humans after the Chernobyl accident.     

长江中上游四大家鱼资源监测与渔业管理

根据1994～2001年的监测结果, 结合历史资料对长江中上游四大家鱼资源现状进行了分析。结果表明：(1)长江中上游四大家鱼在渔获物中的比列呈下降趋势 ;(2)四大家鱼群体结构中低龄鱼比重上升,高龄鱼比重下降;(3)1997～2001年监利江段四大家鱼鱼苗径流量分别为35.87亿尾、27.47亿尾、21.54亿尾、28.54亿尾和19.04亿尾,与1981年该江段67亿尾相比,分别下降46.5%、59.0%、67.9%、57.4%、71.6%。针对影响长江四大家鱼资源的主要因素,提出了保护长江四大家鱼繁殖和栖息地,保持天然水域的相对稳定,降低长江四大家鱼捕捞强度,加强渔政管理等一系列保护长江四大家鱼的措施。     

Levels of organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers in fish species from Kahramanmaras, Turkey

The levels of organohalogenated contaminants, such as organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were measured in four fish species (Acanthobrama marmid (kalashpa), Cyprinus carpio (carp), Chondrostoma regium (nose-carp), and Silurus glanis (wels)) from the Sir Dam Lake, Kahramanmaras, Turkey. These species were selected for their characteristic feeding behaviour and their importance to local human fish consumption. DDTs were the predominant organohalogenated contaminants in all species, with the p,p'-DDE contributing to more than 90% to the total DDTs. Other OCPs, such as hexachlorocyclohexane (HCH) isomers, chlordanes and hexachlorobenzene (HCB) were found at much lower levels in all five species. The levels of PCBs and PBDEs (on wet weight basis) were lower than in similar species from European or American freshwater systems. PBDE data were measured for the first time in fish species from Turkish environment. Lipid-based concentrations of OCPs, PCBs and PBDEs were higher in wels than in the other species and this was related to its piscivorous feeding mode and to its higher lipid content. Contrarily, concentrations of pollutants in nose-carp were the lowest, in agreement with its more herbivorous diet. A preferential accumulation in muscle compared to liver was observed for all OCPs, PCBs, and PBDEs in wels and carp, while in nose-carp, a preferential accumulation in liver was observed only for PBDEs, p,p'-DDT and PCBs. Racemic amounts for alpha-HCH were measured in all investigated muscle and liver samples, except for carp muscle.     

Fetal methylmercury exposure as measured by cord blood mercury concentrations in a mother-infant cohort in Hong Kong

This study was designed to examine newborn infants in Hong Kong prenatally exposed to levels of methylmercury considered to increase risk of neurotoxic effects and to examine subject characteristics that modify the degree of prenatal mercury exposure. Mercury concentrations in 1057 sets of maternal and cord blood samples and 96 randomly selected maternal hair samples were measured. Subject characteristics were measured or collected by questionnaire. Of the 1057 cord blood samples collected only 21.6% had mercury concentrations less than 29 nmol/L (5.8 micro g/L). Median maternal hair mercury concentration was 1.7 ppm. The geometric mean cord to maternal blood mercury ratio was 1.79 to 1. Increasing maternal fish consumption and maternal age were found to be associated with increased cord blood mercury concentrations. Marine fish consumption increased cord blood mercury concentrations more than freshwater fish (5.09%/kg vs 2.86%/kg). Female babies, maternal alcohol consumption and increasing maternal height were associated with decreased cord blood mercury concentrations. Pregnant women in Hong Kong consume large amounts of fish and as a result, most of their offspring have been prenatally exposed to moderately high levels of mercury. In this population, pregnant women should choose freshwater over marine fish and limit fish consumption.     

Persistent halogenated compounds in aquaculture environments of South China: implications for global consumers' health risk via fish consumption

This study examined the potential sources of persistent halogenated compounds (PHCs), including organochlorine pesticides, mainly DDXs (sum of o,p'- and p,p'-DDT, -DDD, and -DDE and p,p'-DDMU) and polybrominated diphenyl ethers, to typical aquaculture environments of South China, determined the relative importance of gill diffusion and fish feeding for exposure of fish to these contaminants and assessed potential health risk for global consumers via consumption of fish from South China. Fish feed is generally a direct and important source of PHCs in both freshwater and seawater aquaculture. In addition, gill diffusion is the predominant uptake route for PHCs (except p,p'-DDMU, o,p'-DDD and -DDT) in farmed freshwater fish, whereas accumulation from the diet is the major route for farmed marine fish. Risks to health of global consumers via consumption of fish from South China are minimal. However, increased risk can be foreseen due to continuous use of brominated fire retardants and electronic waste importation to China.     

A critical review of measures to reduce radioactive doses from drinking water and consumption of freshwater foodstuffs.

Following a radioactive fallout event, there are a number of possible intervention measures to reduce radioactive doses to the public via the surface water pathway. We have critically reviewed the options available to decision-makers in the event of radioactive contamination of surface waters. We believe that the most effective and viable measures to reduce radioactivity in drinking water are those which operate at the water treatment and distribution stage. Intervention measures to reduce concentrations of radioactivity in rivers and reservoirs are expected to be much less viable and efficient at reducing doses via the drinking water pathway. Bans on consumption of freshwater fish can be effective, but there are few viable measures to reduce radioactivity in fish prior to the preparation stage. Lake liming and biomanipulation have been found to be ineffective for radiocaesium, although the addition of potassium to lakewaters appears promising in some situations. Lake liming may be effective in reducing radiostrontium in fish, though this has not, to our knowledge, been tested. De-boning fish contaminated by strontium is probably the most effective food preparation measure, but salting and freezing can also reduce radiocaesium concentrations in fish. The provision of accurate information to the public is highlighted as a key element of countermeasure implementation.     

运动消耗对草鱼幼鱼游泳能力的影响

以草鱼幼鱼（体长80~97 cm，体重96~134 g）为研究对象，采用实验室专利装置研究了不同运动消耗状态下的草鱼幼鱼游泳能力。结果表明：在正常状态下草鱼幼鱼的临界游泳速度[WTBX]（Ucrit）为711±060 BL/s，耗氧率（MO2）与流速（U）方程拟合为MO2=4705+419U123，耗氧率随着流速的增大而增大，且草鱼的有氧运动效率较高。在4种运动消耗状态（06Ucrit、08Ucrit、10Ucrit、12Ucrit）流速下运动1 h草鱼的消耗后临界游泳速度（Upcrit）分别为：725±135、633±06、626±08、560±04 BL/s，临界游泳速度随着前期消耗流速的增大而减小，相应的耗氧率方程拟合为：MO2=38269+465U144，MO2=44526+4223U146，MO2=46611+4790U149，MO2=60034+3883U151。运动消耗会导致草鱼的有氧运动效率降低，同时随着运动消耗速度的增加有氧运动效率随之降低。研究结果认为在设计以草鱼为主要过鱼对象的过鱼设施时，鱼道内的流速不应大于08Ucrit，以使鱼类顺利通过。针对不同过鱼对象游泳特性进行设计的鱼道能够提高鱼类通过鱼道的效率     

浙江北部低洼田湿地农业种养结合模式的环境效应

浙江北部地区地势低洼，种粮易涝，严重制约当地农业的发展。2010年以来，作为湿地农业农作制度的创新，“水生作物 鱼类”种养结合模式在当地得到迅速发展。为了完善种养高效综合配套技术，在嘉兴市秀洲区3个农场开展了不同种养模式（藕 鱼和菱 鱼模式）的对比试验，对池塘水质、底质特征以及大气负氧离子浓度进行了分析。结果表明种养结合模式对池塘水质有一定改善作用。虽然养殖鱼类后水体有机污染有一定程度加重，但由于水生作物的吸收作用，使得水体氮磷含量明显降低。与菱 鱼模式相比，鱼塘种植莲藕后，对水质的改善效果更为明显。对底质的分析表明，鱼塘种植水生作物后，底泥中速效钾含量增加明显，尤其是在种植莲藕后。另外，由于施用化肥以及当年不收割引起的藕叶、茎杆等腐烂分解，使得藕 鱼模式池塘底泥中速效磷和总氮含量大幅增加，分别增加329.1% 和361.9%。对种养结合区域大气负氧离子浓度测定结果表明，种养结合开发利用有利于改善周边区域空气质量     

基于过鱼效果评估的涵洞鱼道堰式挡板性能研究与分析

为研究涵洞式鱼道的内部结构对鱼道水力特性和过鱼性能的影响,利用FishXing软件对江西昌栗高速公路涵洞的过鱼障碍进行了预测与评估,并针对评估结果提出了涵洞内部结构的水力特性优化方案。改造后的涵洞鱼道监测数据证实,通过在内部铺设高低相间的堰式挡板系统,能够将涵洞池室内的水流速度相对平滑涵洞提升约30%,同时相邻池室间的水位差也整体下降。不同体积流量下涵洞鱼道过鱼效果的RFID(Radio Frequency Identification)射频识别结果显示,草鱼的成功通过率要明显高于鲫和鲤,其值分别为50%,26. 41%和7. 6%;涵洞的水流流量由0. 378 m3/s增至0. 429 m3/s,草鱼上行至涵洞上游入口处的平均所需时间和最短时间均有一定幅度的下降,而鲫平均消耗时间则延长了35. 15%,同时草鱼和鲫的折返率也有小幅上升。