广东经济鱼类不饱和脂肪酸的含量分析与组成特征评价

采用水解提取-气相色谱法测定鱼肉中脂肪酸的含量和组成,采用元素分析仪-同位素比值质谱法（EA-IRMS）测定鱼肉碳稳定同位素比值（δ¹³C）.开展广东沿海地区主要经济鱼类肌肉脂肪酸的含量分析及组成特征评价研究.研究表明,25种经济鱼类鱼肉中主要含有单不饱和脂肪酸、n-6和n-3系列多不饱和脂肪酸,以及少量反式脂肪酸（TFAs）;鱼肉的优势脂肪酸为油酸（OA）、亚油酸（LA）和二十二碳六烯酸（DHA）;鲻鱼含有较高的二十碳五烯酸（EPA）和DHA,合计370.0 mg·（100 g）^-1;鲻鱼鱼肉中TFAs的含量（280.0 mg·（100 g）^-1）远高于其它品种鱼类;鲢鱼和黑鲷EPA+DHA的含量较高,分别为（154.4±100.0 mg·（100 g）^-1和1287±291.1 mg·（100 g）^-1,两种鱼均具有较好的商业开发价值;统计学分析结果表明了鱼类的不饱和脂肪酸在组成上具有种属差异,揭示了浮游食性的鱼类其鱼肉组织中MUFAs、n-6 PUFAs以及n-3 PUFAs的含量高于底栖食性的鱼类.鱼肉脂肪酸的组成差异较大,表现为品种、空间以及食性差异.建议市民在日常膳食中丰富食鱼的种类和数量,警惕过多地食用单一品种鱼类（尤其是鲻鱼）而导致TFAs摄入过多的风险,从而确保鱼类脂肪酸的平衡摄入.     

汉江流域有毒鱼类区系分布特征

准确辨识有毒鱼类区系分布是研究有毒鱼类生态适应情况的前提。基于野外调查数据和历史资料,对汉江有毒鱼类的区系组成、毒性类型、食性和空间分布进行了分析。结果表明,汉江流域分布有58种有毒鱼类,占鱼类总物种数的46.77%。58种有毒鱼类隶属于6目10科33属,以鲤形目、鲇形目和鲈形目为主。汉江流域有毒鱼类毒性类型包括胆毒(31种)、刺毒(23种)、血清毒(2种)、卵毒(1种)和肝脏毒(1种);食性主要以肉食性和无脊椎动物食性为主,分别占有毒鱼类总物种数的37.93%和29.31%。在空间分布上,上游河段有毒鱼类物种数显著多于中下游河段。其中,大鳞黑线(Atrilinea macrolepis)、齐口裂腹鱼(Schizothorax prenanti)、司氏(Liobagrus styani),以及拟鲿属的乌苏里拟鲿(Pseudobagrus ussuriensis)、细体拟鲿(Pseudobagrus pratti)、盎堂拟鲿(Pseudobagrus ondon)、凹尾拟鲿(Pseudobagrusemarginatus)等7种有毒鱼类仅分布于汉江上游河段,圆口铜鱼(Coreius guichenoti)和白缘(Liobagrus marginatus)2种有毒鱼类仅分布在中游河段,长江鲟(Acipenser dabryanus)仅分布在下游及河口江段。Jaccard相似性指数分析结果表明,各江段有毒鱼类的物种组成相似性较高。ANOSIM (Analysis of Similarities)检验分析结果显示,Global R=0.99(P<0.01),表明各江段有毒鱼类的毒性类型存在显著的空间差异。研究结果可为淡水有毒鱼类资源保护与利用及有毒动物生态适应演化研究提供基础数据。     

淮河干流基于生态流量的目标鱼类选择研究

基于目标物种的生境需求,确定合理的生态流量过程对河流生态系统保护和修复至关重要.与以往主观选择珍稀鱼类或者主要经济鱼类作为推求生态流量的目标物种不同,从产卵环境和摄食环境等方面对淮河干流目标鱼类的筛选进行研究,运用层次分析法构建判断矩阵,计算各备选鱼类的排序权值,筛选淮河干流对生境要求具有代表性的目标鱼类.结果表明,鳊鱼对淮河干流水生生物的生境需求具有较好代表性,可作为淮河干流生态流量估算的目标鱼类.本研究为缺失珍稀特有物种的河流如何选择用于生态流量计算的目标生物,提供了一种有效的方法.     

长江上游合江江段鱼类早期资源与向家坝水库生态调度效果初步研究

合江江段是长江上游干流保持河流生境、适宜喜流水性鱼类栖息的重要江段.为了掌握合江江段鱼类早期资源动态,分析向家坝水库生态调度的效果,于2020年向家坝水库生态调度前后,开展了鱼类早期资源逐日监测.研究期间,共采集到鱼类早期资源5目10科38种(属),其中仔鱼29种(属)、鱼卵19种(属),包括特有鱼类6种.广适应性和喜...     

Applying a Large,Statewide Database to the Assessment,Stressor Diagnosis,and Restoration of Stream Fish Communities

In this report, predictions of the species that were expected to occur at stream sites were generated and probable stressors to fish species that were predicted to occur but were absent were diagnosed. Predictions were generated based on the hierarchical screening method of Smith and Powell (1971, Am. Mus. Novit. 2458, 1–30), using fish abundance in conjunction with 25 environmental variables at 895 sites. The sites were sampled throughout Maryland and represent the entire range of environmental quality from severely degraded to minimally degraded. Stressor variable values that exceeded tolerance thresholds for species that were expected to occur, but were absent, were considered to be probable stressors. This method was tested for efficacy in stream site assessments and stressor diagnosis using an independent data set. Sites that were classified as degraded according to the IBI and to non-biological criteria had fewer predicted species present compared to minimally influenced sites, indicating that the proportion of predicted species present accurately represents the biological integrity of a stream site. The nine stressors that were applied to the test data set accounted for species absences in 43.7% of degraded sites. Impervious land cover was the most common stressor identified. In addition to assessing stream biological integrity and identifying stressors to fish species, this approach also provides tolerance thresholds for predicted fish species that are useful endpoints necessary to plan effective restoration of fish species in Maryland.     

Contrasting Global Trends in Marine Fishery Status Obtained from Catches and from Stock Assessments

Abstract: There are differences in perception of the status of fisheries around the world that may partly stem from how data on trends in catches over time have been used. On the basis of catch trends, it has been suggested that about 70% of all stocks are overexploited due to unsustainable harvesting and 30% of all stocks have collapsed to <10% of unfished levels. Catch trends also suggest that over time an increasing number of stocks will be overexploited and collapsed. We evaluated how use of catch data affects assessment of fisheries stock status. We analyzed simulated random catch data with no trend. We examined well‐studied stocks classified as collapsed on the basis of catch data to determine whether these stocks actually were collapsed. We also used stock assessments to compare stock status derived from catch data with status derived from biomass data. Status of stocks derived from catch trends was almost identical to what one would expect if catches were randomly generated with no trend. Most classifications of collapse assigned on the basis of catch data were due to taxonomic reclassification, regulatory changes in fisheries, and market changes. In our comparison of biomass data with catch trends, catch trends overestimated the percentage of overexploited and collapsed stocks. Although our biomass data were primarily from industrial fisheries in developed countries, the status of these stocks estimated from catch data was similar to the status of stocks in the rest of the world estimated from catch data. We conclude that at present 28–33% of all stocks are overexploited and 7–13% of all stocks are collapsed. Additionally, the proportion of fished stocks that are overexploited or collapsed has been fairly stable in recent years.     

上海黄浦江水系常见鱼类重金属含量及健康风险评价

黄浦江是兼具饮用水源、航运、排洪排涝、渔业、旅游等功能的上海“母亲河”,鱼类资源丰富。为了解黄浦江水系鱼类重金属污染状况,测定了黄浦江水系15种优势鱼类和主要经济鱼类肌肉中Cu、Zn、Fe、Mn、Pb、Cd、Cr、As、Hg的含量。结果表明,除As外,所有鱼体中的重金属含量均低于国家标准限值或农业行业标准限值。综合污染指数分析结果显示:淀山湖水域翘嘴鲌、大鳍为重金属中度污染(2.0<P_综≤ 3.0),为重度污染(P_综>3.0);苏州河水域翘嘴鲌、兴凯为中度污染,大鳍为重度污染。健康风险分析结果显示,除As外,Cu、Zn、Pb、Cd、Cr、Hg、Mn等的健康风险指数均小于1,对人群的健康风险不显著。复合重金属危害系数(TTHQ)分析结果显示:黄浦江水域似鳊的TTHQ值为0.957;苏州河水域光泽黄颡鱼、刀鲚、似鳊、翘嘴鲌、䱗、大鳍、日本鳗鲡、兴凯的TTHQ值均大于1;淀山湖水域泥鳅的TTHQ值接近1,翘嘴鲌、黄颡鱼、䱗、大鳍的TTHQ值大于1。以上鱼类均存在复合重金属健康风险。目前,淀山湖水域仍有专业渔民开展捕捞作业,因此,应对当地居民重金属健康风险作长期监测。     

Assemblage stability in stream fishes: A review

We quantified the stability of nine stream fish assemblages by calculating coefficients of variation of population size for assemblage members. Coefficients of variation were high and averaged over 96%; indicating that most assemblages were quite variable. Coefficient of variation (CV) estimates were not significantly affected by: (1) years of study, (2) mean abundance, (3) familial classification, or (4) mean interval between collections. We also detected minor regional differences in CVs. The high variability exhibited by many stream fish assemblages suggests that it may be difficult to detect the effects of anthropogenic disturbances using population data alone. Consequently, we urge managers to exercise caution in the evaluation of the effects of these disturbances. More long-term studies of the ecological characteristics of undisturbed stream fish assemblages are needed to provide a benchmark against which disturbed systems can be compared. We suggest that CVs are a better estimator of population/assemblage stability, than either Kendall's W or the standard deviation of the logarithms of numerical censuses. This conclusion is based on the following reasons. First, CVs scale population variation by the mean and, hence, more accurately measure population variability. Second, this scaling permits the comparison of populations with different mean abundances. Finally, the interpretation of CV values is less ambiguous than either of the aforementioned metrics.     

长江中游四大家鱼产卵场的生态水文特性分析

青鱼、草鱼、鲢鱼、鳙鱼是长江流域重要的经济鱼类,但近几年其资源量急剧下降,大量水利工程的修建及河道整治是导致其资源量下降的重要原因之一。为了保护四大家鱼种质资源,确定四大家鱼产卵、繁殖同水文情势的关系,为大型水利工程的生态调度提供依据,研究选取长江中游四大家鱼产卵期的9项相关生态水文指标,分析其在四大家鱼产卵场及非产卵场之间的差异。分析结果表明,所选取的9项生态水文指标在产卵场断面和非产卵场断面没有显著差异,它们只是刺激四大家鱼产卵的必要条件,而非充分条件。同时,选取葛洲坝下典型产卵场江口断面,对比分析该断面在三峡工程正式运行前后四大家鱼产卵期内生态水文情势的变化。结果表明,所选取的9项生态水文指标大多无明显差异,个别指标因三峡蓄水略有变化,但由于三峡蓄水后时间序列较短,且2004~2006年长江来水情况较为特殊,因而目前尚无法定量化三峡工程的修建对下游四大家鱼产卵场的影响。     

河口及邻近海域鱼类优先保护次序的评价模型

正确评价河口及邻近海域鱼类优先保护次序,对河口生态管理以及维持生物多样性具有重要意义,而鱼类优先保护次序评价指标体系和评价方法研究是珍稀鱼类保护的基础。在实地调查和资料收集的基础上,借助专家咨询和相关研究成果提出了由物种濒危系统、遗传价值系统和物种价值系统3个子系统及其指标集组成的鱼类优先保护评价指标体系,确定了评价等级和标准。为克服权重确定的主观随意性,基于信息熵原理确定各指标的客观权重,在此基础上,引入理想点法进行鱼类优先保护多目标决策评价,进而建立了鱼类优先保护次序的评价模型,最后以建立的模型对漳卫新河口及邻近海域鱼类优先保护次序进行评价。结果表明,计算方法简便,评价结果合理,在河口生态管理中具有一定的应用价值