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1.
转Bt基因植物中外源基因时空动态表达的研究现状   总被引:5,自引:0,他引:5  
在转Bt基因植株中 ,外源基因的时空动态表达对于害虫的防治和转基因安全评价管理具有重要意义。利用生物测定法和酶联免疫吸附测定法 (ELISA) ,对植物不同组织在同一发育阶段、同一组织在不同的发育阶段以及不同转基因植株的外源基因的时空动态表达进行研究。本文综述了转基因植物中外源基因时空动态表达的研究进展和现状。  相似文献   

2.
在大棚水泥池内种植两个Bt玉米(5422Bt1和5422CBCL)及其同源常规玉米5422,研究了种植Bt玉米及秸秆还田过程中根际土、根围土、3层根外土(0~20、20~40和40~60 cm)中Bt蛋白含量的时空动态特征及其对土壤养分含量的影响.结果表明: 种植Bt玉米和常规玉米后,根围土(种植后90 d)和3层根外土(种植后30、60和90 d)中均检测到少量的Bt蛋白(含量<0.5 ng·g-1),在Bt玉米5422Bt1和5422CBCL根际土中则分别检测到1.59和2.78 ng·g-1的Bt蛋白.玉米秸秆还田后,Bt蛋白能在3 d内快速降解,在还田后第7天只检测到少量的Bt蛋白.与常规玉米5422相比,种植Bt玉米5422Bt1 90 d后根围土和3层根外土中有机质、速效养分(碱解氮、速效磷和速效钾)和全量养分(全氮、全磷和全钾)含量均没有显著差异;5422Bt1秸秆还田60 d后0~20 cm土层的有机质和全氮含量显著升高,速效钾含量显著降低,而其他养分指标则没有显著差异,20~40 cm和40~60 cm土层的所有养分指标均没有明显差异.种植Bt玉米5422CBCL后根围土中仅速效磷含量显著低于种植常规玉米5422,但0~20 cm土层中全磷含量显著提高,其他养分指标均没有差异;还田5422CBCL秸秆后仅0~20 cm土层的速效磷含量显著高于常规玉米5422.研究结果表明,通过玉米根系分泌和秸秆分解进入土壤的Bt蛋白不会在土壤中累积,对养分含量也基本没有显著影响.
  相似文献   

3.
中国海洋渔业产业生态系统脆弱性时空演化及影响因素   总被引:3,自引:0,他引:3  
李博  金校名  杨俊  韩增林  苏飞 《生态学报》2019,39(12):4273-4283
海洋强国战略以及蓝色农业计划的实施亟需加强海洋渔业可持续发展。以脆弱性为切入点,采用三轴图法剖析中国海洋渔业产业结构,从敏感性、应对能力两方面构建海洋渔业产业生态系统脆弱性指标体系,运用Topsis法和障碍度模型分析2001—2015年中国海洋渔业产业生态系统脆弱性时空演变特征及其影响因素。结果表明:①2001—2015年中国海洋渔业产业结构单一且长期处于初级阶段;②时间维度上,以2008年为节点中国海洋渔业产业生态系统脆弱性呈现由小幅波动向大幅提升转变的阶段性特征;③空间维度上,中国海洋渔业产业生态系统脆弱性空间分布呈现南高北低的集群化特点,依据系统脆弱性等级演变轨迹将中国海洋渔业产业生态系统脆弱性划分为"U"型、"线性上升"型、"波浪"型、"平稳"型脆弱性演化结构;④增强海洋渔业近海海域环境整改力度、优化海洋渔业产业结构、发展远洋渔业、加强海洋灾害预警、引进先进科技设备和优秀专业人才是降低中国海洋渔业产业生态系统脆弱性的有效措施。  相似文献   

4.
落叶松人工林施肥对土壤酶和微生物的影响   总被引:15,自引:2,他引:15  
陈立新 《应用生态学报》2004,15(6):1000-1004
以落叶松(Larix gmelinii)二代1年、一代14年和34年人工林为研究对象,对林地进行了不同施肥实验处理.结果表明,施肥能不同程度地促进或抑制土壤酶活性和土壤微生物数量,尤其是对根际土壤生理活性影响效果更为明显.相同处理对不同发育阶段土壤酶活性和土壤微生物数量的影响效果不同.二代1年生幼林地最佳施肥方案是处理9,其土壤过氧化氢酶活性、蛋白酶活性、多酚氧化酶活性、脲酶活性、蔗糖酶活性、微生物总量、细菌数量、放线菌数量和真菌数量分别比对照提高413.49%、22.10%、20.56%、220.00%、49.46%、238.88%、247.24%、106.70%和366.67%;一代34年生最佳施肥方案是处理5。根际与非根际土壤过氧化氢酶、蛋白酶、多酚氧化酶、脲酶和蔗糖酶活性、微生物总量、细菌数量、真菌数量分别比对照提高30.44%、16.91%、0.22%、43.06%、124.18%、119.92%、87.66%、17.57%、24.55%、77.01%、168.62%、251.85%、183.33%、250.0%、38.24%和128.57%;一代14年生幼龄林需要适量的氮肥和有机无机混合肥,较理想的施肥方案为处理2和处理9,处理2根际与非根际土壤过氧化氢酶活性、蛋白酶活性、脲酶活性分别比对照提高44.39%、94.83%、4.62%、13.98%、10.70%和129.76%.处理9根际与非根际土壤微生物总量、细菌数量、真菌数量分别比对照增加176.49%、266.63%、198.04%、275.56%、66.67%和143.75%.  相似文献   

5.
棉花植株中的黄酮类化台物是重要的抗病虫害物质。运用高效液相色谱技术,对转Bt基因棉花主要抗虫黄酮类化合物的种类、含量和时空动态进行了初步探讨。结果表明,棉花组织中主要抗虫黄酮类化台物(包括异斛皮苷、芳香苷和槲皮素等)能够用HPLC方法检测并进行定量;异树皮苷、芳香苷和树皮素的含量均以花瓣中最高,花萼、苞叶和棉铃中较少;棉花生长中后期顶端嫩叶中抗虫黄酮类化合物的含量明显高于苗期.不同组织不同生长期的主要抗虫黄酮类化合物含量有一定的差异,所起的抗虫作用也有所不同.  相似文献   

6.
中国海洋渔业水域环境研究现状及展望   总被引:1,自引:0,他引:1  
渔业水域环境是水生生物赖以生存、繁衍的最基本条件,优良的渔业水域环境是海洋渔业持续发展的物质载体与必然条件。近年来中国海洋渔业水域环境状况日趋严峻,依据海洋渔业水域监测数据,分析了中国海洋渔业水域环境的现状;概括了中国海洋渔业水域环境面临的主要问题及破坏原因;综述了海洋渔业水域环境保护及修复对策的研究现状,并对今后的研究工作提出了方向与内容上的展望。  相似文献   

7.
铁胁迫诱导的赤潮异弯藻细胞生化组成变化   总被引:5,自引:0,他引:5  
研究了铁胁迫对赤潮异弯藻细胞生化组成的影响.结果表明。铁胁迫下的细胞内所有色素浓度均降低,同富铁条件相比。铁胁迫下的细胞内叶绿素a浓度降低2倍多。叶绿素c也有相当程度的降低,因此,铁胁迫下的胞内叶绿素c与叶绿素a的比率变化不大.铁胁迫下的细胞内类胡萝卜素的含量降低了1.5倍,因此在铁胁迫下的细胞内类胡萝卜素相对于叶绿素a的比例升高。碳水化合物含量随培养基内铁浓度降低而下降,与铁丰富条件(10μmol·L-1)相比,受铁胁迫的细胞可溶蛋白电泳图谱中17kDa和55kDa附近的带明显增加,而在20kDa和35kDa附近的蛋白带降低  相似文献   

8.
转双基因烟草对棉铃虫的杀虫活性评价   总被引:15,自引:0,他引:15  
以含Bt杀虫蛋白基因(单基因)烟草和常规烟草为对照,系统测定了含Bt与豇豆胰蛋白酶抑制剂蛋白基因(双基因)的抗虫烟草对棉铃虫不同龄期幼虫的杀虫活性。结果表明:1 ̄3龄幼虫取食转双基因烟草3d后死亡率为80.5% ̄99.3%,取食6d后死亡率达100%,均显著高于转单基因烟草。2龄幼虫取食转基因烟草3d后死亡率为80.5% ̄99.3%,取食6d后死亡率达100%,均显著高于转单基因烟草。2龄幼虫取食  相似文献   

9.
北疆棉区Bt棉及土壤中Bt毒蛋白含量测定   总被引:1,自引:0,他引:1  
目的:转Bt基因抗虫棉植株中Bt毒蛋白含量测定.方法:采用ELISA法对转Bt基因植株中毒蛋白含量进行了定量检测.结果:在所检测的样品中,叶片中Bt毒蛋白含量最高,其次是蕾、铃、花瓣、花苞叶、蕾苞叶、花柱,而在根中的含量较低,土样中没有检测到Bt毒蛋白;不同生育期的顶叶中Bt毒蛋白含量差异显著,其在苗期叶片中最高,蕾期次之,花期、花铃期开始降低,而铃期和吐絮期又有一定的增加.结论:Bt基因在植株体内的表达随着器官的不同,生育时期的不同而表现出时空动态变化.  相似文献   

10.
转Bt基因抗虫棉的生态风险及治理对策   总被引:12,自引:3,他引:9  
评述了转Bt基因抗虫棉的生态风险及治理对策。其生态风险主要表现在目标害虫的抗性和对非目标生物群落的变化。目标害虫与转基因抗虫棉的互相作用和抗虫棉杀虫毒素的时空表达方式是目标害虫抗性发展的主要途径。在转基因抗虫棉田中,虽然对目标害虫的防治次数大为减少,但害虫和天敌群落的稳定性仍不如常规棉田,某种次要害虫大发生的可能性较大。认为将转基因抗虫棉纳入综合防治体系并培育更加高效的抗虫棉是治理目标害虫抗性和防止次要害虫上升的重要措施。  相似文献   

11.
The interactions between seabirds and fisheries pose significant threats for the seabird species such as incidental capture. In contrast, several species of seabirds meet part of their energetic requirements through the use of fisheries discards. Knowledge about the relationship between at-sea distribution of Procellariiformes and fisheries is a key tool in marine ecosystem management. We analysed the spatio-temporal relationship between the areas used by 16 satellite-tracked breeding adults of the Southern Giant Petrel and fisheries distribution and catch at the Patagonian Shelf. We also determined the time spent by adults in different marine jurisdictions. Results indicated a marked spatio-temporal association between birds and fisheries, mainly trawlers. The Southern Giant Petrels concentrated their foraging effort over Argentinean waters. The use of an abundant and predictable food source provided by the fisheries discards may be one of the factors affecting the dynamics of the Southern Giant Petrel populations in Patagonia, Argentina.  相似文献   

12.
Competition between marine mammals and fisheries for marine resources-whether real or perceived-has become a major issue for several countries and in international fora. We examined trophic interactions between marine mammals and fisheries based on a resource overlap index, using seven Ecopath models including marine mammal groups. On a global scale, most food consumed by marine mammals consisted of prey types that were not the main target of fisheries. For each ecosystem, the primary production required (PPR) to sustain marine mammals was less than half the PPR to sustain fisheries catches. We also developed an index representing the mean trophic level of marine mammal's consumption (TL(Q)) and compared it with the mean trophic level of fisheries' catches (TL(C)). Our results showed that overall TL(Q) was lower than TL(C) (2.88 versus 3.42). As fisheries increasingly exploit lower-trophic level species, the competition with marine mammals may become more important. We used mixed trophic impact analysis to evaluate indirect trophic effects of marine mammals, and in some cases found beneficial effects on some prey. Finally, we assessed the change in the trophic structure of an ecosystem after a simulated extirpation of marine mammal populations. We found that this lead to alterations in the structure of the ecosystems, and that there was no clear and direct relationship between marine mammals' predation and the potential catch by fisheries. Indeed, total biomass, with no marine mammals in the ecosystem, generally remained surprisingly similar, or even decreased for some species.  相似文献   

13.
In developing regions, coastal communities are particularly dependent on small-scale fisheries for food security and income. However, information on the scale and impacts of small-scale fisheries on coastal marine ecosystems are frequently lacking. Large marine vertebrates (marine mammals, sea turtles and chondrichthyans) are often among the first species to experience declines due to fisheries. This paper reviews the interactions between small-scale fisheries and vulnerable marine megafauna in the southwestern Indian Ocean. We highlight an urgent need for proper documentation, monitoring and assessment at the regional level of small-scale fisheries and the megafauna affected by them to inform evidence-based fisheries management. Catch and landings data are generally of poor quality and resolution with compositional data, where available, mostly anecdotal or heavily biased towards easily identifiable species. There is also limited understanding of fisheries effort, most of which relies on metrics unsuitable for proper assessment. Management strategies (where they exist) are often created without strong evidence bases or understanding of the reliance of fishers on resources. Consequently, it is not possible to effectively assess the current status and ensure the sustainability of these species groups; with indications of overexploitation in several areas. To address these issues, a regionally collaborative approach between government and non-governmental organisations, independent researchers and institutions, and small-scale fisheries stakeholders is required. In combination with good governance practices, appropriate and effective, evidence-based management can be formulated to sustain these resources, the marine ecosystems they are intrinsically linked to and the livelihoods of coastal communities that are tied to them.  相似文献   

14.
Bycatch remains one of the most significant fisheries issues in the world and its monitoring and reporting is now expected in many regions. This paper provides a global synthesis of the data that are available on one of the most controversial components of bycatch, that associated with the capture and discarding of endangered, threatened and protected (ETP) species in marine commercial and artisanal fisheries. We examine the available literature regarding estimates for the key taxa in this category of bycatch (seabirds, turtles, sea snakes, marine mammals, sharks, rays and teleosts) and use the data to try to provide a total global estimate. We estimate (albeit quite imprecisely) that at least 20 million individuals of such species are discarded annually throughout the world. However, there remain far too many gaps and uncertainties across fisheries and regions in the information to provide any robustness (or variance) around such an estimate, nor to determine the actual fates of these animals (many may survive). This is exacerbated because: (1) the occurrences of such species are often rare and controversial and so go either unnoticed and/or unrecorded; (2) different levels of protection are afforded to different ETP species in different countries and fisheries and; (3) discarding practices vary greatly across a hierarchy of spatio-temporal scales and according to individual fishing conditions and procedures—the latter affecting actual mortalities. Nevertheless, there have been major initiatives established in recent years to provide better data on such interactions in addition to novel fishing methods and practices that reduce them and also improve the survival of discarded individuals. This paper discusses the data currently available and the quite significant gaps that remain.  相似文献   

15.
The paper reviews the main findings of rocky shore and subtidal nearshore experimental marine ecology (EME) in cold and temperate marine ecosystems during the past four decades. It analyzes the role of EME in coastal management and conservation. The historical development of strategies for managing single or multispecies fisheries are reviewed. The published results show over-exploitation and depletion of more than 60% of the fish stocks and a lack of connection between the management of fisheries and results derived from experimental marine ecology. This is mainly due to: (a) the different temporal and spatial scale at which most marine ecologists and fishery managers operate; (b) the lack of long-term fishery monitoring and adaptive techniques for management; and (c) limitations in the design of experiments on fisheries. Large-scale oceanic perturbations, due to combinations of excessive resource exploitation and environmental variability coupled with present trends in management approaches are discussed. Modern approaches and tools for management of fisheries, such as Adaptive Management (AM), Territorial User Rights in Fisheries (TURFs), Individual Transferrable Quotas and Non-Transferrable Quotas (ITQs, INTQs) are discussed in the context of small-scale fisheries and EME. Published views on limits of applied ecological research with regards to management of fisheries are discussed. Linkages between EME, marine conservation and the establishment of Marine Protected Areas (MPAs) and experimental exclusions of humans are highlighted. Results derived from MPAs, such as: (a) species or community trophic cascades, and (b) the role of key-stone species and species interaction strengths, are discussed. It is concluded that the role of EME in conservation has been greater than has been the case in management of fisheries. The potential to link EME, conservation and the management of fisheries is exemplified through the proposed establishment in Chile of a connected network of Scientific Reserves, MPAs and TURFs sites. The final conclusion is that to cross-fertilize EME, conservation and management, there are three main challenges: (1) to end the traditional view of approaching the management of fisheries and marine conservation as contradictory/antagonizing issues; (2) to improve communications between experimental marine ecology and the management of fisheries through the implementation of experimentation and adaptive management; (3) to improve linkages between marine conservation, the management of fisheries and social sciences.  相似文献   

16.
In this paper, species diversity of demersal fish communities was analysed over an area covering about 45,000 km2 of the Italian side of the Strait of Sicily (central Mediterranean). Fish abundance data come from a 10-year series (1994–2003) of experimental bottom trawl surveys carried out within the framework of the international program MEDITS. A simple GIS-based method was proposed to identify areas supporting high or low values of diversity and evaluate their temporal stability. A well-defined spatio-temporal pattern in diversity emerged from the analysis, with some areas of great ecological relevance being identified. Importantly, the greatest diversity within the fish communities was consistently seen at the offshore bank on the western part of the south Sicilian shelf (Adventure Bank). The site also supports high total biomass of demersal resources and shows the presence of species of great concern to fisheries. Results suggest that Adventure Bank represents a priority site for investigating the possibility of innovative management of marine ecosystems and demersal fisheries in offshore zones.  相似文献   

17.
In contrast to terrestrial farming or aquaculture, little, if any, welfare regulation exists that constrains how fishes are handled or killed in wild‐capture marine fisheries. Given that welfare in wild‐capture fisheries is moving further up the public agenda, an unbiased, dispassionate account of what happens to fishes caught in wild‐capture marine fisheries is needed so as to identify where the main animal welfare issues exist.  相似文献   

18.
Concepts and issues in marine ecosystem management   总被引:2,自引:0,他引:2  
Ecosystem management means different things to different people, but the underlying concept is similar to that of the long-standing ethic of conservation. Current interest in marine ecosystem management stems from concerns about overexploitation of world fisheries and the perceived need for broader perspectives in fisheries management. A central scientific question is whether the effects of harvesting (top down) or changes in the physical environment (bottom up) are responsible for major changes in abundance.Historically, ecology, fisheries biology, oceanography, fisheries management and the fishing industry have gone somewhat separate ways. Since the 1980s, increasing attention has been given to multispecies aspects of fisheries, the linkages between oceanography and fish abundance and more holistic approaches to fisheries management.Sorting out the causes and effects of fluctuations in fish abundance is complicated by the lack of reliability of fisheries statistics. Discards, dishonesty and the inherent logistic difficulties of collecting statistics all combine to confuse interpretation. The overcapacity of fishing fleets and their unrestricted use are widely recognized as a contributing cause to overfishing and declines in fish stocks in many parts of the world.Ecosystem management, as shorthand for more holistic approaches to resource management, is, from a fisheries management perspective, centred on multispecies interactions in the context of a variable physical and chemical environment. Broader perspectives include social, economic and political elements which are best considered pragmatically as a part of the context of fisheries management.Objectives in marine ecosystem management are varied. From a biological perspective, an underlying principle of management is commonly assumed to be a sustained yield of products for human consumption. Whether that should be taken to mean that the yield should always be of the same products is less certain. Fishing commonly changes the relative abundance of species of fishes. Thus, a biological objective should specify the species mix that is desired.Concern for the maintenance of global diversity has generated a substantial literature on threatened and endangered species. In general, it has not been considered likely that marine fish species could be rendered extinct and greatest attention has been given to marine mammals, sea birds and sea turtles. The provision of marine parks and sanctuary areas are obvious first steps in providing a measure of protection, at least for the less widely ranging species.Related to the current concepts of ecosystem management are expressions such as ecosystem health and ecosystem integrity which are given a wide range of different meanings, none of which are readily translated into operational language for resource management. These and similar expressions are best assessed as rhetorical devices. The essential components of ecosystem management are sustainable yield, maintenance of biodiversity and protection from the effects of pollution and habitat degradation.Theory for marine ecosystem management has a long history in fisheries and ecological literature. Ecological models such as Lotka-Volterra equations, ECOPATH, trophic cascades and chaos theory do not give practical guidance for management. Fleet interaction and multispecies virtual population analysis models hold more promise for fisheries managers.Alaska provides particular opportunities for developing new concepts in fisheries management. Statistics of catch are good, stock assessments are at the state-of-the-art level and management has been prudent. Debate is active on the causes of substantial changes in abundance of many species including marine mammals, because substantial changes in the fisheries have been accompanied by major changes in oceanographic conditions.As elsewhere, the resultant changes may be a consequence of top-down and bottom-up effects. The bottom part is beyond human control, and ecosystem management is centred on managing the top-down or fisheries component in the context of special measures of protection for particular species.Whether that is a realistic goal depends in part on how much special protection is to be afforded to which species. Marine mammals, for example, are given high priority for special protection, but like fisheries they too may have significant roles in shaping the structure of marine ecosystems. Eventually, ecosystem management must come to grips with the question of how much protection of particular species is desirable in achieving optimal use of living marine resources.  相似文献   

19.
Oceanic uptake of anthropogenic carbon dioxide (CO2) is altering the carbonate chemistry of seawater, with potentially negative consequences for many calcifying marine organisms. At the same time, increasing fisheries exploitation is impacting on marine ecosystems. Here, using increased benthic‐invertebrate mortality as a proxy for effects of ocean acidification, the potential impact of the two stressors of fishing and acidification on the southeast Australian marine ecosystem to year 2050 was explored. The individual and interaction effects of the two stressors on biomass and diversity were examined for the entire ecosystem and for regional assemblages. For 61 functional groups or species, the cumulative effects of moderate ocean acidification and fishing were additive (30%), synergistic (33%), and antagonistic (37%). Strong ocean acidification resulted in additive (22%), synergistic (40%), and antagonistic (38%) effects. The greatest impact was on the demersal food web, with fishing impacting predation and acidification affecting benthic production. Areas that have been subject to intensive fishing were the most susceptible to acidification effect, although fishing also mitigated some of the decline in biodiversity observed with moderate acidification. The model suggested that ocean acidification and long‐term fisheries exploitation could act synergistically with the increasing sensitivity to change from long‐term (decades) fisheries exploitation potentially causing unexpected restructuring of the pelagic and demersal food webs. Major regime shifts occur around year 2040. Greater focus is needed on how differential fisheries exploitation of marine resources may exacerbate or accelerate effects of environmental changes such as ocean acidification.  相似文献   

20.
Thorpe  J. P.  Solé-Cava  A. M.  Watts  P. C. 《Hydrobiologia》2000,420(1):165-184
The application of genetic techniques to invertebrate fisheries is in many ways essentially similar to that in vertebrate (i.e. finfish) fisheries, for which there is already an extensive body of published data. However, there are also relative differences which lead to particular problems in the use of genetic data to study commercially important invertebrate species. The main role for genetics of both vertebrates and invertebrates has been, and is likely to continue to be, the identification of groups of interbreeding individuals as the basis for a fishery. It is in the identification of the breeding unit that the genetic differences between vertebrates and invertebrates can be of practical significance. The genetic breeding unit, usually called a 'stock' in fisheries biology, generally shows a certain uniformity of size in most marine fish which have been studied. Smaller or less mobile fish (e.g. flatfish) may only range a few tens of kilometres to their breeding grounds, whilst in more mobile, particularly migratory pelagic species (e.g. Scombridae), the area occupied by a stock is likely to be far greater and for a few (e.g. large pelagic elasmobranchs), a single unit of stock may be almost circumglobal. However, marine fish generally, particularly those large or plentiful enough to be of commercial interest, are likely to be fairly mobile and in many cases the order of mobility is likely to be in the region we might predict from our knowledge of the biology and habits of the species. In the genetic assessment of `stocks' for invertebrate fisheries, we face a number of additional problems, mostly related to the large evolutionary range of invertebrates exploited and their widely different biology. Although in Europe and North America marine invertebrate fisheries may be thought of as being mainly for decapod crustaceans and bivalve molluscs, globally commercially important marine invertebrate fisheries range from sponges to squid and include such diverse groups as sea cucumbers, barnacles, krill, octopuses, cuttlefish, sea anemones, ascidians, polychaetes, sea urchins, gastropods and jellyfish. An obvious feature of many of these invertebrates is that the adult (i.e. commercial) stage of the life cycle is sessile (e.g. barnacles, sponges, ascidians) or of very limited mobility (e.g. sea anemones, sea urchins, bivalves, gastropods), with the result that the dispersive phase of the life cycle is the larva. Other groups (e.g. krill, jellyfish) are planktonic or nektonic and may cover very large distances, but, unlike fish, have little control over the distance or direction of travel, whilst some of the open ocean pelagic squid are more mobile than most fish and may migrate thousands or kilometres to spawning grounds. The very low mobility of both larva and adult in some invertebrates indicates that dispersal, and hence stock size, is likely to be low and that, therefore, stocks are far more vulnerable to overfishing than in most fish species. An additional difficulty is that genetic studies to date indicate a remarkably high incidence of cryptic speciation in marine invertebrates, sometimes even in comparatively well studied commercially important species. Thus, although to date marine invertebrate fisheries have not received the same level of attention from geneticist as finfish fisheries, it is clear that for invertebrate fisheries genetic data are relatively far more important if a fishery is to be exploited without being endangered.  相似文献   

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