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1.
While sterilizing a cat, a mummified pup is found in her abdominal cavity. Further examinations suggest that a primary abdominal pregnancy can be excluded, although no perforation or scar of the uterine wall is noticed during operation.  相似文献   

2.
  1. Shark-based tourism continues to be a rapidly growing industry, and thus understanding the impacts of such activities is essential to mitigate the potential negative effects on the target species. The consequences of provisioning on whale sharks (Rhincodon typus) are not fully understood, although changes to the local environment, ecology, behaviour, and site visitation patterns have been highlighted. Here, the scarring patterns of whale sharks were investigated at a provisioning site in Oslob, Cebu, Philippines, as an indicator of the physical impacts of tourism activities on individual sharks. Photographic identification was used to attribute scars to individual animals (n = 152) between March 31, 2012 and January 31, 2015.
  2. Scars were categorized by type and body location, and were compared with non-provisioned aggregations in Australia, Mozambique, and Seychelles. Oslob whale sharks were more scarred than other studied populations, with 94.7% (n = 144) having at least one scar, and with 90.8% (n = 138) having more than one scar. Scarring incidence was found to be significantly higher in sharks that regularly visited the provisioning site, and analysis of scarring over time in highly resident sharks showed that all individuals gained scars through periods of consistent re-sightings. A significantly higher incidence of minor scar types was found, most commonly on the dorsal side of the animal, probably resulting from sustained proximity to boats and ropes throughout the provisioning activities. The consequences of interactions with propeller boats were observed, despite a ban on their use in the provisioning site, highlighting the risk to the species beyond the study site.
  3. We recommend the strict enforcement of a minimum distance between boats and sharks, a zero-contact policy during interactions, the expansion of the provisioning site, and the implementation of a no-boat-access zone around the perimeter of the provisioning site to mitigate potential collisions.
  相似文献   

3.
SUMMARY: The survival of Japanese whiting Sillago japonica and by-catch species captured by a sweeping trammel net was examined to assess the effects of differing species, captured conditions, and body lengths on survival, in Tateyama Bay, Chiba Prefecture, Japan. All the live samples were kept in laboratory tanks for 4 days of successive survival observation. The survival ratio of the Japanese whiting varied by the captured conditions. The fish captured by pocketed condition was 27% surviving at the fourth day, which was significantly higher than the gilled and entangled fish. Most of the by-catch species survived for 4 days. About 60% of dead Japanese whiting were observed to have scar injury and damage on the body surface. For the by-catch species, the body damage occurred only in stripedfin goatfish Upeneus bensasi , Temminck's surfperch Ditrema temmincki , and tidepool gunnel Pholis nebulosa . Therefore, it suggests that the conservation measure through catch-and-release may be an appropriate method for most by-catch species, but not for the Japanese whiting.  相似文献   

4.
对典型病症为体表腹甲严重斑块状充血、甚至出血,体表某些部位出现溃疡,严重的会口鼻充血、流血,内脏肝、脾、肾肿大的病鳖进行了病原菌鉴定分析。从肝脏中分离菌株ARC090812,经VITEK-32全自动细菌鉴定仪鉴定,结果为嗜水气单胞菌。药敏实验显示分离菌株对庆大霉素、丁胺卡那霉素等药物敏感,对恩诺沙星及强力霉素中度敏感。致病性实验表明,半数致死量LD50为7.87×108CFU/mL。  相似文献   

5.
Successive exposure to aquaculture‐related stressors may compromise the allostatic capacity of African catfish and lead to allostatic overload and poor welfare. Therefore, we tested the effect of (i) feeding during the light or dark phase, (ii) density (51 fish per 140 L versus 51 fish per 43 L) and (iii) altered available resting space/shelter on stress handling were studied in African catfish (Clarias gariepinus). Available resting space/shelter was manipulated by providing PVC‐tubes in the tanks. Growth, baseline stress load (cortisol and osmolality), metabolism (glucose, lactate and non‐esterified fatty acids) and aggression (measured by skin scar incidence) were assessed. Upon completion of the experimental period, we determined the adaptive capacity of the fish by the response to air exposure. We show that night‐feeding enhances growth and lowers feed conversion ratio compared to day‐feeding. No effects of density were found for baseline stress hormones, basal metabolism or aggression. Low density seems to stimulate aggressive behaviour after air exposure. Unexpectedly, providing PVC‐tubes under high‐density conditions increased aggression, raised baseline cortisol levels and decreased basal metabolism as well as growth; also the endocrine response to air exposure was stronger. We argue that these effects relate to a reduction in available space, i.e. a further increase in density, or to an increased competition for shelter. Overall, our data suggest that night‐feeding optimizes growth and that care should be taken in using objects as shelter/enrichment for African catfish.  相似文献   

6.
2008年~2011年研究了人工养殖条件下的施氏鲟Acipenserschrenckii(6)×达氏鳇Husodauncus(早)杂交后代(f谷称大杂交)的生长特性。结果表明:1~7龄大杂交体长、体重相对增长率及生长指标随年龄的增长而逐渐下降,呈“异速生长一等速生长一异速生长”的变化趋势。不同年龄大杂交的体长与体重均呈幂指数关系,R2值变幅为0.95~0.99。其中,1-3龄大杂交a值〉3,呈强异速生长。此后随年龄的增加,异速生长减弱,发育趋向均匀。5龄时a值为2.94接近3,7龄a值为2.63〈3。大杂交肥满度随年龄增加而增大,其与体重的相关性(R2=0.94)高于与体长的相关性。采用7种生长方程对不同年龄大杂交的体长生长和体重生长进行拟合,其中Gompertz、Quadratic、VBGF和Cubic4种生长方程式对大杂交体长生长的拟合效果较好,除Cubic生长方程外,其它6种生长方程对其体重生长的拟合度均较低。7种生长模型中,均以Cubic生长方程对大杂交的体长生长和体重生长的拟合R2值最大,RSS值最小,说明Cubic生长方程对不同年龄大杂交的生长具有最好的拟合效果,拐点体重、体长和年龄分别为28.53kg、82.11cm和4.22龄。  相似文献   

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In cattle purulent arthritis of the distal interphalangeal joint is a severe and relatively frequent disease of the claw. In many cases it is possible to avoid amputation and to maintain the function of the affected digit by resection of the joint. Surgical procedure and results of joint resection, carried out in 281 cases, are described. In 71 of the 281 animals a clinical and radiographical reexamination could be performed between three months and six years after surgery. In 59 cases (83%) the function of the operated claw was unimpaired. Ankylosis of the joint was observed in 41 (58%) cases and occurred between 7 to 12 months post op. The operated claw supported the contralateral claw in its weightbearing function. The animals could be kept on slatted floor as well as on pasture. In comparison to amputation the animals can be used longer after joint resection.  相似文献   

9.
纤维绳索强度分析中线性回归与曲线拟合法的比较   总被引:1,自引:1,他引:1  
马海有  郭亦萍 《海洋渔业》2006,28(4):304-308
介绍了对绳索的断裂强度与直径关系的直线回归、幂函数拟合及自然对数拟合的方法,图示比较了三种函数图形及其与标准指标值的偏差,分析了这三种方法所得结果的差别,其中自然对数函数的返回值与标准指标值最为接近。以自然对数函数对聚丙烯、聚乙烯和聚酰胺绳索产品国际标准建立了断裂强度与直径关系的数学模型。采用这种数据分析方法,在制定系列规格的产品标准中确定技术指标,比较具有规律性。  相似文献   

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This article builds on the literature investigating productivity and efficiency in the Norwegian salmon farming industry. The objective of this article is to investigate the determinants of inefficiency. We use a stochastic frontier approach that allows the estimation of a production function and an inefficiency function. The sources of inefficiency can be separated into temporary shocks and factors that lead to permanent efficiency differences. The results indicate an improvement in technical efficiency over time. This improvement can partly be explained by a restructuring of the industry, with firms becoming bigger and more specialized, as well as by improvements in government regulations. The inefficiency that is still present is mainly the result of temporary shocks. Disease outbreaks seem to be the most important of these temporary shocks, as disease problems lead to early harvesting or destruction of the fish and thereby, obviously, increase inefficiency.  相似文献   

12.
根据滁河干流六合段各水功能区水环境现状和水质目标的要求,利用一维S-P水质概化模型,在一定的设计水文条件、水质背景、排污口位置及排污方式的条件下,以化学需氧量(COD)和总氮(TN)作为主控因子进行了该江段纳污能力的计算。在90%设计保证率下COD和TN的总纳污能力分别为7333t/a和289t/a;该河段COD和TN实际纳污量分别为11676t/a和1647t/a;各水功能区中,COD和TN入河量较多的是工业用水区和龙池保留区,其实际纳污量分别为4274t/a和691t/a;污染物消减率最大的功能区为工业用水区,COD和TN消减率分别为68.6%和91.3%,说明工业用水区是该河段水环境治理的重点区域。  相似文献   

13.
本研究以天津中新生态城污水库为研究对象,通过建立生态服务价值评价指标体系,对比分析生态修复工程实施前污水库和实施后清净湖的生态服务价值变化,评估修复工程投入与工程实施后产生的生态效益。结果表明,污水库生态服务价值估算为2546.78万元/a,调节服务是主要服务类型,占总价值量的99.46%;生态修复工程(总投资1.5亿元)实施后,生态服务价值估算为15093.05万元/a,文化服务成为主要服务类型,占比87.8%。对比分析发现,生态修复工程带来的生态效益明显增加,总价值增加了5.9倍,其中景观美学增值明显。研究以清净湖为例初步探讨了生态修复工程对污染生态系统服务价值的影响,为开展类似城市水体生态修复项目决策提供科学依据和借鉴。  相似文献   

14.
To optimize feeds and feed management for barramundi ( Lates calcarifer ), an improved factorial model is required. A growth function describing weight gain by barramundi as a function of fish weight and water temperature was derived from farm and laboratory data. The function was of the form: A maintenance energy demand function was also derived on a similar form and two functions combined to form the basis of a factorial model for this species. An assessment of protein and energy utilization efficiency was undertaken to examine the effect of fish size on the estimation of these parameters. Fish size had a significant effect on energy utilization efficiency on a linear basis, but no such difference was observed if the data were considered using non-linear methods. Protein utilization efficiency was also observed to be clearly non-linear, and although protein deposition capacity differed with fish size, the efficiencies of protein utilization were not affected. Using this factorial model, optimal iterative feed specifications were defined for a range of fish sizes and formulation constraints. A feed demand model was also developed based on the demand for digestible energy.  相似文献   

15.
生态系统模型是研究食物网结构和功能的重要方法,Ecopath是一个功能强大的生态系统模型,可量化生态系统结构和功能特征,进行现状评价、过程模拟及趋势预测,最终提出适宜的生态系统管理措施。本文对Ecopath方法进行了简要介绍,归纳了其在国内外水生态系统研究和管理中的应用实例,初探了其应用过程中存在的几点问题:在模型建立过程中,研究区域的生物种群动态及食性组成等基础研究的不足,会导致模型P/B、Q/B参数输入的准确性不高;对Ecopath模型的敏感度分析、输入参数的不确定度分析及模拟效果的评估,在该模型发展及应用过程中可能更受到关注。  相似文献   

16.
Assigning individual fish to populations using microsatellite DNA markers   总被引:11,自引:0,他引:11  
New statistical developments combined with the use of highly polymorphic microsatellite DNA markers enable the determination of the population of origin of single fish, resulting in numerous new research possibilities and applications in practical management of fish populations. We first describe three main categories of methods available, i.e. (i) assignment tests and related methods, (ii) discriminant function analysis and (iii) artificial neural networks. In all these, individuals can be assigned to the population from which their multilocus genotypes are most likely to be derived. Assignment tests are based on calculations of the likelihood of multilocus genotypes in populations, based on allele frequencies. Discriminant function analysis is based on multivariate statistics, whereas artificial neural networks formulate predictions through exposure to correct solutions. Assignment tests are the methods of choice when considering genetic data alone, whereas discriminant function analysis and artificial neural networks may be useful when genetic data are combined with, for instance, morphological and ecological data. Assignment tests can be used to assess the genetic distinctness of populations, for discriminating among closely related species and to directly identify immigrants or individuals of immigrant ancestry, and thereby study patterns of dispersal among populations, including sex‐biased dispersal. In a conservation context, assignment tests can be used to assess the genetic impact of domesticated fish on wild populations and for determining if extant fish populations are in fact indigenous or descendants from stocked fish or strayers, and they can be applied in forensics, for instance to reveal poaching. Assignment tests are at present most useful for studies of freshwater and anadromous fishes owing to stronger genetic differentiation among populations than in marine fishes. However, some genetically divergent populations of marine fishes have been discovered, which could be used as natural laboratories for studying dispersal and gene flow. It is foreseen that ongoing developments in statistical methods, combined with improved techniques for screening large numbers of loci, will permit assignment methods to become standard tools in studies on the biology of fishes.  相似文献   

17.
So far, there are a number of fish genome projects, including experimental and economically important fish that provide available DNA sequence information. However, the function of a gene cannot be deduced only by its DNA sequence. Therefore, a technique with which to investigate the function of the fish gene is needed. Gene knockdown (GKD), or antisense technology, is now being used as a powerful technique to study gene functions in living organisms. GKD effects result from the introduction of an antisense molecule into living cells. The antisense agents bind to target messenger RNA, thus inactivating the target gene expression. The appropriately spatial inhibitory effects on protein production from corresponding gene resulted in the phenotypic change. Therefore, the function of the gene can be understood. To date, there are a number of antisense molecules that can affect efficient GKD in fish. These include antisense oligonucleotides, small interfering RNA, and ribozyme. These antisense molecules cause specific gene inhibitor effects with different mechanisms. The various antisense mechanism types facilitate a number of GKD applications with various approaches in animals. In this review, we demonstrate the characteristics of each antisense molecule, its mechanism, and its application, especially for gene functional analysis in fish.  相似文献   

18.
The function of adenylyl cyclase (AC)-dependent and calcium (Ca2+)-dependent signal transduction pathways in mediating gonadotropin-stimulated testosterone (T) synthesis in croaker follicular cells was investigated. Both pathways are critical regulators of steroidogenesis in these cells. Stimulation of steroidogenesis by modulators of AC-dependent cell signaling is partially dependent on the presence of extracellular Ca2+, although AC function does not appear to be mediated by the Ca2+ pathway in croaker follicular cells.  相似文献   

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