鲑鳟鱼类寄生虫病研究进展与展望

鲑鳟鱼类是典型的冷水性鱼类,经济价值高,是世界重要经济养殖鱼类之一。然而,随着其养殖产量攀升,养殖密度增大,养殖环境恶化,鲑鳟鱼类寄生虫病的发生和危害也日趋频繁和严重,严重制约了产业的健康发展。鲑鳟鱼常见的、危害较为严重的寄生虫主要包括三代虫(Gyrodactylus)、鱼虱(Caligus rogercresseyi)、阿米巴原虫(Neoparamoeba perurans)、脑碘泡虫(Myxobolus cerebralis)、苔藓鲑四囊虫(Tetracapsuloides bryosalmonae)和库道虫(Kudoa spp.)。这些寄生虫生活史简单,繁殖速度快,大多寄生在鱼体表面及体内的各种组织器官上,导致鱼体生长缓慢、抵抗力下降,引起鱼体损伤并造成死亡。在防治方法上,通过物理控制、化学药物和免疫治疗相结合的方法进行综合防控。本文对鲑鳟鱼常见寄生虫病领域的研究和成果进行简要综述,以期为鲑鳟鱼寄生虫病的研究和防治提供参考。     

鱼类增殖放流站亲鱼池数值模拟研究

增殖放流是目前普遍采用的减缓水利水电工程对鱼类影响的措施之一。亲鱼培育是增殖放流的关键环节,亲鱼培育池是增殖放流站中的关键设施。鱼池不同流速流场区域的形成与亲鱼池的结构型式、工艺尺寸、进出水流量等多种因素有关,特别是针对国内山区急流河段水电工程鱼类增殖放流站亲鱼池的数值模拟研究还处于空白。采用计算流体力学(CFD)方法对亲鱼培育池流场进行了模拟,从亲鱼适宜流速区间最大化的角度,通过标准k-ε模型对最常用圆形和矩形两种不同结构型式的鱼池进行三维建模,分析比较了不同结构尺寸圆形池与矩形池的水力学条件,建议优先采用圆形池作为亲鱼培育池的型式,最适宜径深比为6∶1～3∶1;场地紧张而采用矩形池时,适宜长宽比为4∶1～2∶1。除流场外,温度、溶氧、排污分布等其他环境因子对鱼类繁殖也有一定的影响。对于特定鱼类,应该根据其生物学特性,适时调整鱼池的流速,满足相关需求。研究结果丰富了国内鱼类增殖放流站亲鱼池结构设计内容,推荐的亲鱼池结构型式可为鱼类增殖放流站设计提供参考。     

六冲河鱼类资源衰退的原因与对策建议

乌江上游主要干流六冲河多年来由于修建水利工程、人为过度捕捞、引进外来鱼种、水域污染、法律监督管理不力,导致该河中的野生优质鱼类趋于低龄化、小型化、低质化,资源量急剧下降,部分名优鱼类濒临灭绝的严峻形势.从加强领导、修建水利工程时应保护鱼类的生存,加快地方特有鱼类驯化养殖,实现人工放流进行资源修复,加强渔政管理等方面来实现对六冲河鱼类资源的保护.     

海水鱼类亲体必需脂肪酸营养的研究进展

脂肪酸营养特别是其中的必需脂肪酸在海水鱼类生殖调控方面具有重要的生理作用。饲料中二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)以及花生四烯酸(ARA)含量在调控海水鱼类性腺发育、排卵、孵化率及仔鱼质量等方面作用显著。本文主要从必需脂肪酸需求量、对繁殖性能影响、对机体脂肪酸存储影响及对内分泌调控作用4个方面归纳总结了海水鱼类亲体脂肪酸营养的研究概况,并重点分析探讨了在内分泌调控方面的研究进展,同时对后续的研究重点提出了一些建议。     

Ecoepidemiology of the effects of pollution on reproduction and survival of early life stages in teleosts

Evidence from the field and laboratory has shown that reproduction and early life-stage survival of several species of teleost fishes have been adversely affected following the release of several classes of synthetic, organic chemicals into the environment. Field studies from many geographic areas over several decades have found associations between exposure to synthetic chemicals in the environment and effects on hatchability, embryological success and larval survival. In more recent research, exposure to sewage treatment and bleached kraft mill effluents has been correlated with changes in reproductive system development and alterations in the endocrine physiology of wild teleost fishes. Loss of fecundity and damage during various stages of development and reproduction have been associated with exposure to endocrine disruptors, including many currently used chemicals. The supporting laboratory studies have confirmed that various wild fish species are sensitive to certain synthetic chemicals at levels of exposure of parts per billion and parts per trillion, concentrations that are biochemically, physiologically, and environmentally relevant. This paper reviews the relevant field and laboratory research, and organizes the studies using the ecoepidemiological criteria of time-order, strength of association, specificity, consistency on replication, coherence and predictive performance. There is sufficient evidence to conclude that ambient concentrations of synthetic chemicals in some regions are at or above concentrations at which certain species could be affected. The viability of fishery resources must be linked not only to the quantity of habitat but also to the quality of habitat.     

Gonadosomatic index and gonad histopathology of Gobius niger (Gobiidea, Teleost) from Bizerta lagoon (Tunisia): Evidence of reproduction disturbance

To evaluate the effect of anthropogenic pollution on fish reproduction in Bizerta lagoon, one of the largest Tunisian lagoons subjected to various anthropogenic and industrial pressures, the gonadosomatic index (GSI) and gonad histology of mature black goby (Gobius niger) were studied. Fish were collected during the breeding seasons from six stations differently impacted and in one reference station located at the seaward entrance of Ghar el Melh (GH) lagoon. In both sexes, we detected the presence of an overall weaker GSI in Bizerta lagoon than in control fish. These GSI alterations were accompanied by histopathological changes. In females, no significant differences in oocyte size were found across all the sample sites. However, a higher incidence of oocyte lesions (atretic oocytes, cytoplasmic retraction and karyoplasmic cluping) was found in stations located near agricultural activity zones. Histological observation of the testes revealed, as well, abnormalities in Bizerta lagoon fish: germ cells syncytium, vacuolated germ cells, melano-macrophage center and increase of gaps in the interstitium between lobules were detected with a high prevalence in stations influenced by industrial and/or urban activities. In addition, association between gonad fish histopathology and the presence of organic pollutants (DTT, PAHs and organotins) in sediment was noted. These results suggest that the chemical pollution in this lagoon may have adversely affected the gonad development of fish. In conclusion, this study is the first histological evidence of reproduction disturbance related to pollution pressure in a fish species inhabiting Bizerta lagoon. The high levels of gonad histopathology recorded raise concerns about the long-term health of fish populations in this lagoon.     

Econometric analysis of the factors contributing to the fish price increase in coastal TURFs in Japan: the case of income-pooling fishery for coastal shrimp “Sakuraebi Sergia lucens”

While rights-based management systems have often been encouraged as effective management tools, few studies have analyzed the effects of those systems empirically. In this article, we have focused on a special form of the territorial use rights in fisheries strategy, namely, an income-pooling system, and examined the effects of this system empirically. Earlier studies have regarded the control of fish landing amount and improvement of the quality of fish as the two main determining factors in such a system. Consequently, in our study, we estimated the relationships between these two factors and the price of fish using the econometric method. The results show that the two factors do indeed have significant effects on price changes.     

The use of immunostimulating herbs in fish. An overview of research

The use of immunostimulants as an alternative to the drugs, chemicals and antibiotics currently being used to control fish diseases in fish culture is attracting the attention of many researchers. In this context, many have focused on the use of medicinal plant products as potential therapeutic measures for modulating the immune response and, specifically, on the use of herbs to prevent and control fish diseases. Medicinal plants (plant remedies) are a deeply rooted component of the cultural heritage of many people from diverse cultures and countries and are, as such, closely linked to the maintenance of good health. The aim of this paper is to review research currently being carried out on the herbs and herbal extracts that have been shown to modulate the immune system of fish. Special attention is given to the use of Chinese and Indian herbs.     

A comparative and evolutionary approach to oxidative stress in fish: A review

Oxidative stress results from an imbalance between the production of reactive oxygen species and the antioxidants defences, in favour of the former. In recent years, the association between oxidative processes, environmental change and life histories has received much attention. However, most studies have focused on avian and mammalian taxonomic groups, with less attention given to fish, despite their ecological and socio‐economic relevance. Here we present a review of the extrinsic and intrinsic factors that influence oxidative processes in fish, using a comparative and evolutionary approach. We demonstrate that oxidative stress plays a key role in shaping fish's responses to environmental change as well as life history strategies. We focus on representative examples to compare and contrast how levels of oxidative stress respond to changes in temperature, salinity and oxygen availability. Furthermore, we describe how emerging threats (i.e. pollution) affect oxidative stress parameters in fish. Oxidative stress indicators are increasingly being used as biomarkers to understand the mechanisms of various human‐induced stressors, but also to understand the physiological consequences of how animals are distributed in space and time and influenced by different life stages. Despite the expansion of the field of ecological oxidative stress, we are only beginning to understand the complex ways in which oxidative stress may interact with both extrinsic and intrinsic factors in fish. We conclude with a research agenda for oxidative research on fish and note that there is need for further research particularly in the area of life history strategies and ecological implications of oxidative status, as this type of research has the potential to help us understand patterns and dynamics relevant to fish conservation.     

Management and restoration of fish communities in Lake Taihu, China

The economic development of the cities around Lake Taihu, China, has caused both environmental changes and ecological succession. The biodiversity of Lake Taihu has declined since 1970. Migratory fish, including anadromous, catadromous and semi-migratory fish, are either extinct or on the verge of extinction in Lake Taihu. Only lake dwellers persist. Several measures have been taken, such as restocking, closed seasons, sanctuaries for enhancement and even introductions to restore some original fish communities. Although these measures have achieved a certain degree of success, increased fishing activities or over-fishing have offset the benefits obtained. Moreover, cultural eutrophication of the lake and the pollution of the waterways connected with the lake are getting worse. This jeopardizes the remaining economically valuable species in the lake. Measures are required not only to control eutrophication and pollution, and to reduce the intensity of fishing, but also to address the wider biodiversity issues.     

Morphology, endocrinology, and environmental modulation of gonadal sex differentiation in teleost fishes

Successful reproduction by an adult depends on the normal ontogenesis of the gonads, a complex process of cellular and histological differentiation that starts early in life. This process is theoretically predetermined by genetic factors and includes sensitisation of the bipotential gonads to endogenous endocrine factors prior to, during and even after commitment to maleness or femaleness. However, young fish are relatively vulnerable to a host of environmental (physical and chemical) factors that can affect this endogenous endocrine axis, disturbing or even overriding the putative developmental pathway. This sexually lability can be exploited to our advantage for the production of monosex fish populations of the most valuable sex for food production or aquarium fish trade. On the other hand, it represents also a potential path for undesirable influences from endocrine-disrupting chemicals and climatic factors, particularly environmental temperature. This paper provides a detailed account of the early histological process of gonadal sex differentiation, with special reference to gonochoristic species, and reviews the criteria employed to positively identify ovarian and testicular differentiation. It also reviews the development of endocrine competence and sensitivity of the differentiating gonads to exogenous influences in the context of the relative stability of genotypic sex determination in various fish species. Sex differentiation in some species seems to be under strong genetic control and may not require endogenous sex steroid production. Conversely, reliance on endogenous sex steroids for gonadal differentiation is observed in other species and this phenomenon is apparently associated with a higher incidence of environment (mainly temperature)-labile sex differentiation. This revised version was published online in July 2006 with corrections to the Cover Date.     

The reproductive brain in fish

In fish as in other vertebrates, the brain is actively involved in the control of reproduction, first by participating, under the influence of external factors, in the establishment of an appropriate endocrine status, but also by allowing synchronization of the partners by the time of spawning. It is now well established that the pituitary gonadotropic function is controlled by multiple stimulatory and inhibitory factors, originating mainly from the preoptic region and the mediobasal hypothalamus, both target regions for sexual steroids. Little is known about the mechanisms involved in the mediation of external and internal factors, however there is indication that internal factors, such as androgens and melatonin, known to trigger particular behavioural and endocrine responses, act both at the level of neuroendocrine territories, but also on sensorial systems, which are the actual sites of action for external factors. This paper represents an attempt to summarize and integrate the recent literature devoted to the different aspects of the brain as a major participant in the complex endocrine and behavioural mechanisms of reproduction in fish.     

Review. Levels of Recirculating Reproductively-related Steroid Hormones in Female Elasmobranchs. Implications for Reproduction in a Captive Environment

Chondrichthyans are a diverse group in terms of reproductive mode, which range from extended oviparity to placental viviparity. Although the reproductive biology of several species has been investigated, the reproductive physiology of only a few species has been reported. Only recently have the physiological factors of reproduction in cartilaginous fishes received attention. The information gained on reproductive cycles (both gonadal and uterine) has shown some similarities as well as differences between species. The serum levels of androgens, oestrogens, and progestins have been examined in several elasmobranch species and it has been shown that they are important in regulating key events in reproduction. The endocrine control of reproduction in elasmobranchs is more similar in many ways to higher vertebrates such as mammals than to teleosts. In general, the role of progesterone becomes more important than that of oestrogen in the transition from oviparity to viviparity. In addition, the roles of peptide hormones such as relaxin and the neurohypophysial hormones become increasingly important in viviparous species as in higher vertebrates. It is vital to understand the environmental and hormonal control of reproduction in elasmobranchs if more success is to be achieved in their reproduction in captivity. Knowledge gained from studies of the endocrine regulation of the reproductive cycle can be used to enhance the reproductive success of captive sharks, skates, and rays. This revised version was published online in August 2006 with corrections to the Cover Date.     

鱼类肽YY与胰肽Y的研究进展

酪酪肽与胰肽Y同属于胰多肽家族,是广泛存在的多功能调节肽;胰肽Y是酪酪肽基因组复制产生的鱼类中特有的神经肽。目前已在多种鱼类中分离得到酪酪肽与胰肽Y的基因,与特定受体发挥生理功能,包括使机体产生饱腹感而食欲下降,减少摄食,降低体质量,在调控养殖鱼类摄食,提高饲料转化率,促进鱼类健康养殖以及消化道、肝胰腺、肥胖等治疗方面发挥重要作用。本文通过概述鱼类中酪酪肽与胰肽Y的结构特征、体内分布、作用的形式及受体、影响因素等生物学功能,为鱼类肽YY及胰肽Y的研究提供参考。     

Reproductive success and fry production of the paiche or pirarucu,Arapaima gigas (Schinz), in the region of Iquitos,Perú

Arapaima gigas (paiche) is the largest scaled fish species living in the Amazon basin. Its biology is both fascinating and misunderstood. In a context of overfishing, hence reduced natural populations, aquaculture of a fish with such interesting characteristics (large size, high growth rate, no intramuscular spines) is an important issue. The development of farming production would also reduce the fishing pressure on natural populations and allow re‐stocking programmes in certain areas. To determine what factors may influence the reproductive success in captivity, data from breeding reports for 2007–2010 were collected among fish farmers in the region of Iquitos. In parallel, we carried out physicochemical measurements in different ponds where these paiches breed, and conducted personal interviews about the general fish management conditions. The results show that reproduction occurs throughout the year but with a higher intensity during the rainy season. It also highlights farms that have performed much better than others, but no single factor except feeding level has been clearly associated with reproductive success. The environmental control of reproduction in paiche, therefore, remains partly mysterious. To deepen this study, we recommend the systematic sexing of breeders, extending reproductive behavioural studies, and examining the limnological factors involved in fry mortality.     

水电站影响下太湖西苕溪鱼类产卵生境及其早期资源与环境因子的关系

水利设施运行影响下的鱼类早期资源发生规律被逐渐关注,坝下区域也成为鱼类产卵生境的关注热点。西苕溪作为太湖上游的重要补充支流,是太湖流域鱼类完成生活史过程的重要载体。为解析电站影响下的坝下河流生境变量与鱼类早期资源的内在联系,本研究于2022年4—7月在西苕溪江东电站坝下的东山段开展了持续90 d的鱼类早期资源调查以及时空格局研究。结果显示,该区域鱼卵日平均密度为(0.5±0.7)ind/m3,仔鱼日平均密度为(0.5±0.6) ind/m3。运用形态学结合分子生物学方法进行种类鉴定,共鉴定鱼类35种,隶属4目14科22属,其中产沉性卵鱼类9种,产浮性卵5种,产黏性卵9种,产漂流性卵12种。5月下旬、6月上旬和6月下旬为产卵高峰期。左右岸样线以沉性卵和以水生植物为黏附基质的产黏性卵鱼类为主,河心样线则以产漂流性卵、产黏性卵和浮性卵鱼类为主。该区域鱼类卵苗数量受水温、流速、水位影响较大,水位、流速是影响鱼类繁殖的主要因子,电站调度对卵苗量有显著影响。基于卵苗收获量、卵苗发育时期等结果,判定该采样区域——西苕溪江东电站坝下东山段为适宜多种鱼类繁殖的复合型产卵场,对太湖流域鱼类多样性和渔业资源...     

Viral infections in cultured fish and shrimps: current status and treatment methods

Aquaculture is growing post-haste in recent years particularly in the fish and shrimp production. The rapid growth of aquaculture and increasing demand for fish have led to a rapid development of the fish and shrimp industry, resulting in increased production of both fish and shrimps. As a result, there is a greater risk of disease outbreaks. Mass mortalities in aquaculture are primarily due to infectious diseases caused by bacteria, viruses, and fungi. Among them, viral diseases are the most devastating, causing huge loss in the production of both cultured fish and shellfishes. There are several effective methods of treatment for these disease outbreaks. This review focuses on various methods of controlling the viral pathogens using various treatment methods like use of medicinal plants and seaweed extracts, bioactive compounds from actinomycetes, vaccines, probiotic microbes, chemicals, nanoparticles, and green synthesis of nanoparticles.

     

山东琵琶岛海域人工鱼礁区鱼类群落物种及功能多样性

为了解山东琵琶岛海域人工鱼礁区鱼类群落物种及功能多样性的时空变化特征,于2020年7月—2021年4月在富瀚国家级海洋牧场示范区开展4个季度的渔业资源和环境因子调查,采用物种多样性指数和基于12个功能性状的功能多样性指数分析了鱼类群落多样性的时空变化及其与环境因子的关系。结果表明,鱼礁区鱼类物种和功能多样性指数均呈现显著的季节变化,而对照区仅功能多样性指数呈现显著的季节变化;Pielou均匀度指数、Simpson多样性指数、功能均匀度指数和功能离散度指数在空间上存在显著差异;Spearman相关性分析结果显示,功能丰富度与物种数和Margalef丰富度具有显著相关关系,功能均匀度与物种数和Pielou均匀度具有显著相关关系;群落特征加权平均数指数(CWM)表明,鱼类群落优势性状组成呈现一定的时空变化特征;冗余分析结果显示,透明度和无机氮对物种多样性指数具有显著影响,而酸碱度、无机氮、溶解氧和透明度则对功能多样性指数影响显著。以上结果说明,鱼类群落物种和功能多样性具有明显的时空变化特征,但变化趋势不一致,表明物种和功能多样性指数在解释鱼类群落差异时存在一定的互补性。